Nightly news begins right now. Announcer from nbc news World Headquarters in new york, this is nbc nightly news with lester holt. Good evening. Round two. The nations midsection taking another wicked weather punch as we come on the air tonight. These pictures in to us just minutes ago from kentucky. Take a look at this. A tornado on the ground there. Part of the second Severe Weather outbreak in as many nights. In oklahoma this evening, residents are still assessing the damage after close to two dozen tornadoes churned across the region just about this time last evening, killing two people. Right now, this map shows in realtime the locations of storm chasers, several of them as you can see clustered in kentucky and indiana, where things are heating up. Gabe gutierrez reports now from the storm zone. Reporter late today, this tornado slicing through mayfield, kentucky, as mi midwest and north texas please dont hit that farm. Oh, my god. Reporter brace for another round of Severe Weather. In oklahoma, recovering from this twister, almost a mile wide captured up close on camera, smothering everything in its way, cutting a threemile path and leaving a trail of destruction. It just blew off its foundation. Reporter at least nine reported twisters. More through oklahoma, killing two people. Lisa buckner lived next to one of them. She barely survived riding out the storm in her storm shelter. I started crying. I was in disbelief. Reporter teenager daniel park home alone, when his dad called to tell him to take cover in the middle of the house. It soon collapsed around him. I was in the bathroom on the ground. Reporter the outbreak spanning six states within hours, at least 22 reported tornadoes. The threat far from over. Tonight the threat of severe he expands from texas to illinois with the biggest threat of supercells in missouri, oklahoma, and parts of northern texas. Electric lines down, fire flashes. Reporter in oklahoma, a firefighter captured this video. Even seasoned First Responders said these tornadoes were heartwrenching. When you hear of the loss of lives, its not easy. Reporter a frantic new search for jamie ramirezs pets trapped in her crumpled home. Theyre our family. Reporter in a region where so much was lost, finally something found. Today the National Weather service said this damage was caused by at least an ef3 tornado with winds topping 136 miles per hour. Now this region is bracing for the possibility of more severe storms tomorrow. But tonight, there are already reports of multiple injuries and multiple buildings damaged from the new tornado in western kentucky. Some of those pictures so close to those tornadoes, gabe, thank you very much. Turning to the race for president. And donald trump saying in an interview today he has narrowed his list of running mates down to five or six candidates. Congress returned in full from recess today to face the new reality of trump as the Presumptive Republican nominee. We get the details from nbcs hallie jackson. Reporter ted cruz mobbed late today, making his return to washington. But making it clear, again, hes not ready to endorse donald trump yet. There will be plenty of time for voters to make the determination who theyre going to support. Reporter cruz cracking the door a bit to get back in the race. If circumstances change, we will always assess changed circumstances. Reporter for his colleagues in congress, the first day back at work since trump became the presumptive nominee. Speaker paul ryan downplaying expectations for thursdays meeting with the candidate. We have to actually unify and do it. Reporter the real concern of some republicans, that trump will drag down the ballot. Marco rubio focusing more on the key reelection races to help the senate keep its gop ma majority. I think the best thing i can do to do that, i think, is to support those who are out there running for the conservative cause. Reporter our nbc News Analysis shows just 12 of 21 republican senators on the ballot in november support trump. Trump Campaign Sources acknowledging those concerns, tell us trump will do whatever he can to assure Party Leaders hes there to help. Much of the talk revolving around not just what trump says, on trade, on immigration, but on how he says it. Is that something youre worried about . What i see happening is a developing and fleshing out of issues, and a change in tone. Reporter senator bob corker dismissing talk he could be a vp pick as trump tells the mix, narrowing down to five or six possible running mates, experienced politicians who can do what trump hasnt proven what he can yet, work with washington. Ahead of those meetings here on the hill, new controversy for donald trump tonight after his campaign included a prominent nationalist on his possible delegates in california. Trumps Campaign Calling it a database error on someone who was rejected and removed from that list two months ago. Lester . Hallie jackson tonight, thank you. The democrats are facing off tonight in West Virginia. The primary there. While Hillary Clinton has shifted her line of attack to donald trump, she continues to struggle to put away Bernie Sanders. But as Nbcs Kristen Welker tells us, she got a big vote of confidence today from Vice President joe biden. Reporter its the strongest sign of support yet from the white house. Vice President Joe Biden predicting Hillary Clinton will win in november. I feel confident hillary will be the nominee, and i feel confident she will be the nextsi president stopping short of an allout endorsement, in an interview he gave last month. Theres no problem. We can elect a woman in this country. Reporter right now clinton leads donald trump nationally by five points in our online poll. But new polls in swing states show statistical dead heats, clinton narrowly leading in florida and pennsylvania. Trump with a slight lead in ohio. But first, clinton has to officially lock up her own nomination. Campaigning today in kentucky. And releasing new ads on radio and television. Thats the job. And shes the one whos proven she can get it done. Reporter its a shift in strategy for clinton who had stopped spending on television to save resources for her likely battle against trump. But with Bernie Sanders poised to win a number of states in may, shes trying to limit her losses and head into the convention on solid ground. Today sanders stng yet in an interview with nbcs chris jensen. Well fight for every last vote. If things go well in the next nine states, weve got a shot to win a majority of the pledged votes. Reporter as clinton campaigns here in kentucky, sanders is poised to win West Virginia tonight, a state that clinton won by nearly 40 points in 2008. But it will largely be a moral victory as this race is nearly mathematically out of sanders reach. Lester . Kristen welker, thanks. A powerful u. S. Senator is demanding answers from facebook over allegations that the social networking giant is biased against reporting conservative oriented news items. Its a story that has a lot of people talking. The company is now responding. Nbcs blake mccoy tells us more. Reporter 163 million americans use facebook. Many probably turn to the trending feature for their news. A running list of stories selected the website said by popularity. But tonight a top demanding to know how that list is compiled. If the news is coming through there, which is represented to be objective and its not, then i think the people deserve the right to know that. Reporter in an article posted monday, one anonymous former employee who helped compile the trending list said stories are picked by editors, not algorithms, and facebook dropped conservative stories, saying it was absolutely biased. We were doing it subjectively. According to the source described as politically conservative, trending topics about mitt romney among others were removed. In a statement facebook Vice President said in part, there are rigorous guidelines in place for the review team to ensure consistency and neutrality. These guidelines do not permit the suppression of political perspectives. Users from across the political spectrum rely on facebook to promote their message. Facebook has the ability to kd of dictate what is popular, whats going to show up higher in their algorithm versus lower, and as a result, it shapes the way that publishers are compiling their news and also sharing it. Reporter today facebook said they have found no evidence of stories being dropped. Late afternoon, one of those stories was tough to miss. Facebook trending is trending. Blake mccoy, nbc news. If youve been to the airport lately or youre a regular viewer of nightly news, you know about the long lines swelling at security lines, and passengers increasingly losing patience. Its gotten so frustrating a Group Representing airlines is asking passengers to share their photos of the long lines, using the i hate the wait. While some major airports are now threatening to fire the tsa. Nbcs joe fryer now with the details. Reporter at chicago ohare today, an hourlong wait to get through security. Its really long. Not looking forward to it. Reporter now travelers are sharing photos of those long lines using the i images are popping up across the country, chicago midway, st. Louis, washington, and orlando, described by one traveler as cattle call insanity. Carolyn hizer recently snapped this picture at jfk. I got to the airport three hours early. And i still barely made my flight. Reporter in some places, time spent waiting in line may rival time spent flying in the air. The problem is so bad, the Port Authority that runs newark, jfk and laguardia airports sent a letter to the tsa warning it could use private security screeners if wait times dont improve. We can no longer tolerate the continuing inadequacy of tsa passenger screening services, it says. They take a lot into consideration before they make decisions like this. This is huge. This will have ripples across our industry. Reporter 22 airports across the u. S. Currently use private security. Most of them are small, but two are not. San francisco and kansas city, and others like seattle and atlanta are the tsa admits it is understaffed. Were hiring and targeting the hiring for the airports with highest volume. Reporter despite the long waits, some travelers are packing patience. Its frustrating. But everybody here would rather be safe than sorry. Reporter even with more hiring, security lines will still be long this summer. Thats because the number of passengers is only expected to grow. Airlines recommend showing up two hours before domestic flights. Another option, signing up for tsa precheck. Lester . Joe fryer, thank you. Late word in the investigation into the death of prince. One of his doctors who wrote him prescriptions has been identified. And police have gotten a search warrant. Were also learning new details about what happened the morning prince was found dead. Nbcs Stephanie Gosk has more. Reporter among many of the Unanswered Questions about princes untimely death, did a local doctor in minnesota tr tonight a search warrant said dr. Michael todd chillenberg examined prince twice, one on april 7th before his plane made an Emergency Landing in moline, illinois, and then again on april 20th, the day before prince died. The warrant which was issued to obtain princes health records, said the doctor was dropping off test results to prince at paisley park when he appeared at the death scene. During questioning by police, he said he prescribed medications for prince, and the unspecified prescriptions were filled at a walgreens. Dr. Schulenberg is a family physician. He told investigators he worked for north memorial clinic. Tonight that hospital tells nbc news that he is no longer an employee there. We reached out to dr. Schulenberg at his private office, but he has not responded. This comes after an attorney for dr. Representative of prince called his client the night before the pop star died for what he described as a lifesaving mission. Stephanie gosk, nbc news, new york. A massive march through north Koreas Capital today marked the end of the ruling partys First Congress in 36 years. An event leader kim jongun used to tout his nuclear capabilities. Now someone very close to kim has won a powerful new role in his regime, his sister. Nbcs bill neely got rare access inside north korea and has more. Reporter mass hysteria as tens of thousands shouted, live forever, to kim jongun, the worlds youngest dictator. Now chairman kim, sworn enemy of america and nuclear arms. North korea leads the world in displays of mass loyalty, and state power. And this extraordinary show is also a message to the world, respect us. Kims leadership is his sister taking the flowers, educated with him in switzerland, helped craft his propaganda and image. Shes being promoted to the ruling committee. A risky business. Kim had his uncle and many other generals executed for stepping out of line. No one does here. At the ruling congress, kims plan for more nuclear arms was hailed as genius. Theyre saluting kim jongun, this parade, this Congress Really is all about him showcasing his control, his power, his image. It ended in flames. And thats the great danger of kims weapons buildup, which the whole world opposes. Bill neely, nbc news, pyongyang, north korea. Still ahead tonight, a growing danger on the roadway. Whats behind the alarming rise of accidents of people driving high. A gunshot nearly ended his life, but instead it began a mission to save the lives of others. E working witha and your doctor to maintain your health. Because in 5 days, 10 hours and 2 minutes you are going to be 67. And on that day you will walk into a room where 15 people will be waiting. 12 behind the sofa, 2 behind the table and 1 and a half behind a curtain. Family surprise but only one of them will make a life long dream come true. Great things are ahead of you when your health is ready for them. At humana, we can help you with a personalized plan for your health for years to come. This is brad. His day of coaching begins with knee pain, when. Hey brad, wanna trade the all day relief of two aleve for six tylenol . Whats the catch . Theres no catch. You want me to give up my two aleve for six tylenol . No. For my knee pain, nothing beats my aleve. I smbut ended up nowhere. A lot now i use this. The nicoderm cq patch with unique extended release Technology Helps prevent the urge to smoke all day. I want this time to be my last time. If you have allergy congestion muddling through your morning is nothing new. Introducing rhinocort® allergy spray from the makers of zyrtec®. Powerful relief from nasal allergy symptoms, all day and all night. Try new rhinocort® allergy spray. What knee pain . D all night. What sore elbow . Advil liquigels make pain a distant memory nothing works faster stronger or longer what pain . Advil. That reminds me. Anyone have occasional constipation, diarrhea. Gas, bloating . Yes one Phillips Colon Health probiotic cap each day helps defend against occasional digestive issues. Live the regular life. Phillips. A new warning about the dangers of driving while high on marijuana. And how unreliable the tests are to determine whether a driver is actually impaired. Nationwide, more than half the drivers rushed to Trauma Centers after traffic accidents have drugs in their system. Usually pot. And fatal crashes are on the rise. Heres nbcs tom reporter they are the faces of lives cut short by other drivers who were high. Brian woods father is the driving force behind duid, for drugs. It turns out the most common drug we find is marijuana, usually in combination with many other drugs. Reporter today 20 states allow medicinal marijuana, four states plus d. C. Allow recreational pot. Were you smoking in the car . Yeah. Reporter in at least two states that have legalized marijuana, a disturbing trend. In colorado, pot makes up 19 of all duis. Fatal accidents in which a driver had marijuana in his or her system up 44 . In washington state, that rate more than doubled according to aaa. Among the victims, 23yearold blake gaston. You are impaired. You are impaired. I have seen impairment. I have seen what impairment does. Reporter blake was hit and killed while riding his motorcycle by a dr he was high. Under pressure, six states have recently passed new dui laws for marijuana. Similar to a blood alcohol level, its a test for the marijuana chemical thc, which aaa researchers say the thc level is meaningless, not an indication of whether somebody is high. Theres nothing to support setting a numerical concentration of cannabis in somebodys body that would allow us to predict they are impaired. Reporter aaa wants a new approach from enforcement. Youre saying im not going to find any weed in this car . Reporter training cops to better detect and document impaired behavior, on the road and at the scene of the crash. Tom costello, nbc news, washington. Up next, big change coming for one of the bestselling beverages in america. Abetic ne. Shoots and burns its way into your day, i hear you. 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The white house announced today that president obama will become the first sitting u. S. President to visit hiroshima during a visit to japan lar the president will travel to the site where the u. S. Dropped an atomic bomb during world war ii, accompanied by the japanese prime minister. Get used to saying this americas for you. Budweiser today is changing its name for the summer to america. Celebrating patriotism and the olympics. That means the labels will say america, too. Budweiser, we should note, is now owned by a belgian company. Up next, he went from patient to doctor. On a mission to save lives. vo if you have type 2 diabetes, you may know what its like to deal with high. And low blood sugar. Januvia sitagliptin is a oncedaily pill that, along with diet and exercise, helps lower blood sugar. Januvia works when your blood sugar is high and works less when your blood sugar is low, because it works by enhancing your bodys own ability to lower blood sugar. Plus januvia, by itself, is not likely to cause weight gain or low blood sugar hypoglycemia . Januvia should not be used in patients with type 1 diabetes tell your doctor if you have a history of pancreatitis. Serious side effects can happen, including pancreatitis which may be severe and lead to death. Stop taking januvia and call your doctor right away if you have severe pain in your stomach area which may be pancreatitis. Tell your doctor right away and stop taking januvia if you have an allergic reaction that causes swelling of the face, lips, tongue, or throat, or affects your breathing or causes rash or hives. Kidney problems sometimes requiring dialysis have been reported. Some people may develop severe joint pain. Call your doctor if this happens. Using januvia with a sulfonylurea or insulin may cause low blood sugar. To reduce the risk, your doctor may prescribe a lower dose of the sulfonylurea or insulin. Your doctor may do blood tests before and during treatment to check your kidneys. If you have kidney problems a lower dose may be prescribed. Side effects may include upper respiratory tract infection, stuffy or runny nose, sore throat, and headache. For help lowering your blood sugar talk to your doctor about januvia. This is lloyd. To prove to you that the better choice for him is aleve. Hes agreed to give it up. Ok, but i have 30 acres to cover by sundown. Well be with him all day as he goes back to taking tylenol. Yeah, i was ok, but after lunch my knee started hurting again so. More pills. Yep. Another pill stop. Can i get my aleve back yet . For my pain. I want my aleve. Get all day minor arthritis pain relief finally tonight, a man on a mission to save lives who found his calling after his own life was nearly lost. Almost a decade ago, he beat the odds with help from a dedicated doctor. As nbcs Kevin Tibbles tells us, that began his journey from being a patient to seeing patients of his own. Kevin d. Morton jr. Reporter a season of new beginnings for freshly minted doctor kevin morton. People call you doctor now . Yeah, its weird. Reporter his moment to celebrate and say thank you. It appears it was a robbery gone bad. Reportein morton was shot while closing up after the night shift at a detroit arbys. One resident said i had a 10 chance of making it through the night. Reporter doctors found massive internal bleeding. But the trauma surgeon was tireless. Call it intuition, experience or a miracle, we put extra sutures in and the bleeding stopped. Reporter after 50 days in the hospital, kevin set his sights on medicine. The compassion, in trying to save my life i just want to pay that forward. Reporter starting next month, dr. Kevin morton begins part of his residency at the very hospital that treated him. This place saved your life. Saved my life. Reporter and at graduation, his doctor was there with he and his family, as she has been since that fate going to give up. We werent going to give up. We had to make it happen. Reporter even the miracles of medicine can still benefit from a human touch. Kevin tibbles, nbc news, detroit. Thats going to do it for us on a tuesday night. Im lester holt. For all of us at nbc news, thank you for watching, and good night. Decision 2016, here is lester holt. Good evening, another primary night in the race for president , and as the polls close in West Virginia, nbc news projects Bernie Sanders is the winner on the democratic side. And donald trump, of course, is the winner on the republican side. As all of his rivals have dropped out. Chuck todd is here. Hillary clinton still has the math on her side. But she cant seem to shake Bernie Sanders. Is this beginning to erode her goals at this point . I dont think it does. She only has to go back eight years to know how this ends, right. Eight years ago, in 2008, in the month of may, we were in the same position, barack obama had this mathematically won, and yet, Hillary Clinton kept winning these may primaries and