Good evening. With a death toll of 4 and 16 wounded, all of them members of the u. S. Military, all of them shot by one man on home soil, tonight the u. S. Army launched a massive investigation into what went wrong and into security within the confines of ft. Hood in texas. The massive home to so much of our nations infantry and mechanized forces. For the ft. Hood community and the u. S. Army, its a second tragedy of course in five years. For the families of the departed, there is only mourning and sadness along with the lingering question of why. We have it covered tonight from texas to puerto rico, the home of the alleged gunman here and one of the victims. Nbcs mark potter starts us off from ft. Hood. Mark, good evening. Reporter good evening, brian. Were learning more tonight about the events leading up to the shooting. Officials dont believe this was a premeditated killing spree. Investigators say they believe shooting suspect ivan lopez acted alone after a confrontation with other soldiers. Some of whom were among his victims. We do have credible information he was involved in a verbal altercation with soldiers from his unit just prior to him allegedly opening fire. Reporter nbc news has also learned lopez told friends he was angry about getting only a single day of leave for his mothers funeral. The three soldiers who are killed here at ft. Hood have all been publicly identified. 38yearold Staff SergeantCarlos Lazaney rodriguez. After serving nearly 20 years in the military, he was planning to retire to puerto rico at the end of the year. Rodriguezs aunt says his destiny took a turn for the worst. He died in the place where he loved to be. 37yearold Sergeant Timothy owens. A counselor and ten year army veteran. He remarried last august. His mother said he loved serving his country. He was going to make a career of it. He only had so many more years to go. Signed up for six more recently. Reporter and Sergeant First Class daniel ferguson. The 39yearold returned safely from afghanistan to lose his life here at home. Fergusons fiancee said he died trying to keep the shooter from entering a room filled with people, and he was not alone in his heroism. We met with one young soldier who with a bullet wound in his abdomen stepped forward to save other soldiers and called 911 to help prevent even further loss of life. Reporter were also learning more about the wounded, including Sergeant Jonathan westbrook. Another afghanistan veteran. I can only imagine what my child was going through to see somebody else get shot down and then realize that, you know, the gun is coming at you next. Reporter in the wake of the shootings here in 2009 and again this week, questions are being raised about security and whether lopez could have been stopped from bringing a gun on post. Out of the nearly 42,000 soldiers assigned to ft. Hood, the vast majority of them live off base. Add to that all the contractors, family members and retirees in the area and more than 100,000 people come on base each day. It wouldnt be realistic to do a pat down search on every single soldier and employee on fort hood for a weapon on a daily basis. Reporter 150 investigators are trying to recover exactly what happened and if there were any warning signs. Mark potter, nbc news, fort hood, texas. This is Stephanie Gosk in begin nia, puerto rico, a small quiet town on the south coast where ivan lopez grew up. Today his family broke its silence for the First Time Since the shooting. In a statement lopezs father offers a prayer for the victims and explains his son was undergoing medical treatment. He must not have been in his right mind, lopezs father says. He wasnt like that. The shooting has shaken people here who have always been proud of their young men and women serving in the military. And there are many of them. Residents here say as many as half of the High School Graduates will enlist. I was two years in the army. Reporter Wilfredo Ramirez lives next door to the home where ivan was raised. Ramirez fought in vietnam. Im proud of being a veteran. Reporter his daughter died fighting in iraq during her third tour. The military is one of very few Job Opportunities for young people here, he told me. Ramirez says enlisting in the military has been a way for his family and other Puerto Ricans like them to feel more american. Nearly everyone that we have spoken to here in this town knows the lopez family. They describe them as hard working and religious. That original disbelief that ivan could have been involved in this shooting is starting to wane. What replaces it, brian, is a lot of sadness here. Stephanie gosk in puerto rico for us tonight mark potter before that. Our thanks to you both. We have an update on the weather impacting millions of americans across a huge part of this country at the start of the spring season. The radar is lit up tonight. Severe storms causing damage in parts of texas, alabama, tennessee, arkansas and to the north theyre also dealing with torrential rains, wiping out roads, triggering floods, mud slides in parts of ohio, indiana, kentucky. To top it all off, would you believe fresh snow on the ground in the upper midwest, up to a foot in parts of the state of minnesota. New job numbers came out today. They tell a number of different stories about our current economy. Employers added 192,000 jobs last month. The Unemployment Rate held steady. 6. 7 . Notably, the number of private sector jobs has now come all the way back since the financial collapse and recession to prerecession levels. The problem is the population has also increased in that time, meaning more people looking for work, leaving the Unemployment Rate stubbornly high. Many of the newly created jobs are in lower paying industries than before. On wall street today, some unrelated factors drove the markets down. The dow finished off 159 points. The nasdaq fell 110. This was a grim day in afghanistan on the eve of important elections in that country. There has been another socalled insider attack. The first to target journalists. An Afghan Police commander opened fire on two veteran Associated Press reporters as they sat in their car inside a base in eastern afghanistan. German born photographer Anja Niedringhaus was killed. Correspondent kathy gannon was injured. Niedringhaus won a pulitzer for her memorable work in iraq, an award she shared with ten fellow ap journalists back in 05. She covered the war in afghanistan since it started. These are some of the remarkable imagines she captured there over the years. Her colleagues at the ap today called her a, quote, vibrant, dynamic journalist with a warm heart and a joy for life. Our chief Foreign Affairs correspondent Richard Engel is back in afghanistan where a lot is changing as u. S. Forces pull back and start their withdrawal. Richard . Reporter good evening, brian. This is a closeknit community. We all know these journalists and it was heartbreaking to learn anja had been killed and we all wish kathy a full and speedy recovery. Afghanistan is in transition. U. S. Troops are leaving, elections are tomorrow. And as u. S. Forces leave, a lot of aid money is going with them putting some of the most important humanitarian projects in this country at risk. Even by afghan standards kandahar, the taliban strong hold is a very traditional place. Women here stay under wraps. Before leaving home, she covers herself head to toe. Then takes the bus to one of the few places where women here can relax and learn. The Kandahar Institute of modern studies, a vocational school. The only one in town where women study english, computer skills and management. This is the schools founder and main teacher. What does this institute mean for the women who go there . Well, it means opportunity. It means freedom. It means hope. It means job. Reporter for parwana, it means even more. The school is her refuge. After she married last year, her husband ordered her to stop coming. But she wouldnt give up. She borrowed books and studied in secret. I try to middle of night i was studying management and i want to bring my assignment. Reporter when her husbands family caught her reading, she says they beat her, starved her, and locked her in a cold room until she had a nervous breakdown. They were uneducated people and i was educated girl. Reporter parwana now lives with her family. She escaped her husband and returned to school. Women here dont just learn. They make connections. Nargis takes classes and practices her english via skype with caroline burk, a grad student in new york. Hello. Hey. Can you hear me . Yeah, i can hear you. Can you hear me . What the experience has taught me is boundless. I learn more every day. Reporter but the school that survived years of violence could close and soon. It has received tens of thousands of dollars from the u. S. State department but that funding ran out in september and wasnt renewed. Now women are being sent home. They are completely disappointed now. And they are looking for hope. Reporter the u. S. Invested heavily to help women here but as american troops leave afghanistan, so does the money. And a light of hope in the heart of taliban country could be extinguished. Richard engel, nbc news, kabul. The search for Malaysia Airlines flight 370 has tonight entered a critical new phase. Those underwater locators have now arrived. They have reached the search zone working around the clock to find the black boxes by listening for the electronic pulse. The problem is time because the batteries are expected to fade. Nbcs katy tur is in kuala lumpur where the flight originated. Good evening, katy. Reporter good evening. It is already saturday morning and were quickly approaching a month. Why is a month important . Well, the batteries on those beacons, the black box beacons begin to run out after a month. So they basically have the weekend to find this plane. To help with that, they have started to deploy the pinger locators we have been talking about. The naval devices are being towed underwater by australian ships. Theyre able to detect a ping from a black box as much as 20,000 feet below the surface. Now above the surface, there are eight countries, 14 planes, nine ships in the indian ocean. And while the search may be going full speed, Everything Else seems to be slowing down. They havent had a News Conference here in kuala lumpur in a week. Theyre shutting down the media center on monday. Theres been no new spottings, new leads, or satellite imagines. If they dont find the plane this weekend, they might have to go into a new phase of looking where theyre using sonar and radar to sweep the ocean floor that is how they found air france a year later. But remember, brian, with air france, they had a debris field. They had a flight path. With this, its basically just an educated guess that its even in the indian ocean. Katy tur in kuala lumpur, malaysia for us. Katy, thanks. Still ahead for us this evening, the earth has awakened beneath los angeles. Now the experts are weighing in on what worries them the most there. And the real story behind a dramatic charge in yellowstone captured on video and getting a whole lot of attention. This past week millions of people in Southern California have been living on shaky ground after the strongest earthquake to hit the l. A. Area in six years and then there have been hundreds of much more minor aftershocks since. The folks who live there are all too familiar with the many fault lines that one beneath them, including the very wellknown San Andreas Fault. Now theyre learning more about something called the puente hills thrust fault which runs right through downtown l. A. And as nbcs Miguel Almaguer reports for us tonight, it has everyones attention. Reporter every day millions cross its path. The 25mile puente hills thrust fault, which slices bel s below neighborhoods, downtown skyscrapers, bridges and freeways. Southern california is the most likely source of a great earthquake, 7. 8 or greater in the United States at this point. Reporter Seismologist Lucy Jones prepares for the inevitable. It may be the notorious San Andreas Fault that ruptures, but what worries her the most is the puente hills fault. A week ago today, a 5. 1 on that fault broke water manes, cracked foundations and triggered a rock slide. Experts say a 7. 5, a big one here, would be catastrophic. This was the epicenter of last weeks quake. An l. A. Suburb packed with middle class homes. Experts say if the big one struck on the same fault line, 18,000 people could be killed, 750,000 left homeless. The problem is bridges arent built to modern earthquake codes and hundreds of buildings are made of vulnerable concrete. L. A. s iconic General Hospital had to be shutdown in 94 after the northridge earthquake. Now its just medical offices. But within five miles of here, six other hospitals could face catastrophic damage in a big quake, including Childrens Hospital los angeles. Just one building, l. A. s hall of justice has taken three years and a quarter billion dollars to retrofit to shore up 11 critical bridges, another 400 million. The mayor fears the big one could be the biggest disaster in u. S. History. We have to make sure we minimize that by seeing fewer structures come down and minimizing the damages and most important the loss of life. What were trying to prevent is the end of los angeles. If we dont do it in time, people will die. Reporter its impossible to predict when the next quake will strike though experts agree the big one is certain to hit. Miguel almaguer, nbc news los angeles. You may recall we started this week documenting the big new u. N. Report on Climate Change and its impact around the world. We wanted to let you know ann curry has spent a year putting together a documentary on the effects of Climate Change, how the experts say the effects are already being felt across the globe. It airs sunday night, 7 00 6 00 central here on nbc. Were back in a moment with a big debate over an iconic piece of american history. Yet another emotional day in boston after the year theyve had. Marathon bombing survivors delivered the world series rings to the red sox at their home opener at fenway. Boston royalty was on hand. Pedro martinez and the former mayor tom menino. And a boston firefighter took this photo of the tribute before the game for the two firefighters killed in the back bay fire a week ago. Nasas incredible cassini spacecraft way out there in the Wild Blue Yonder of space has discovered what appears to be water the size and depth of Lake Superior beneath the frozen surface on one of saturns moons. Cassini first sent back photos of water vapor above the surface of that moon back in 05. It has since zoomed in for a closer look. If you have flown into new york, youve seen them out the window. If youre old enough you remember when they were new. The once gleaming futuristic structures of the 1964 worlds fair. The observation towers designed by the renowned architect Phillip Johnson and opened by Lyndon Johnson are now part of a vast, abandoned and rusty urban landscape. The 50th air force of the fair is now 18 days away, and the city must soon decide whether to restore these monuments from the era when anything seemed possible or tear them down. A video showing bison running down the road through Yellow Stone National park has so far been viewed by over 1 Million People on the web. Mostly because a lot of people believe it foretells the coming eruption of some sort of super volcano beneath the surface of the park. The park service says its not so, nor where they running because of the most recent earthquake there. The park has about 3,000 tremors a year. They say the animals are always on the move. Mostly because theyre looking for food. When we come back, remembering 13 extraordinary days that changed the world. Finally here tonight, a new play has opened in washington, d. C. With just four characters, three heads of state and one first lady. Its called camp david. Its all about former president jimmy carter who devoted two weeks of his presidency and a substantial chunk of his leadership to forging a peace in the middle east. And no pressure on the playwright, the former president and first lady were sitting right there in the audience last night along with nbcs andrea mitchell. Reporter before the moment of victory, the first arab peace treaty there was a struggle. 13 days, 2 avowed enemies and an american president , arguing, cajoling, pleading with them to make peace. I would say those 13 days were among the most dramatic of my life. Reporter the carters were back in washington last night for the opening of camp david the play. With richard thomas, once john boy on the waltons and fbi Supervisor Frank gad on the americans. The challenge of playing a living president who was really in the audience last night. It would have been a good night for an understudy. Reporter history focuses on carter, men knock began and sadat. Gentlemen, please. Reporter but Lawrence Wright realized there should be another pivotal character, the first lady. Hows the peacemaking coming along . Reporter i realized the character of Rosalyn Carter was the person who was making peace among the peacemakers. Its a perfect breaker, circuit breaker, if you will. She had emotional access to the characters the way jimmy did not. Reporter just as in real life, the talks almost fail. It was a crazy idea. Completely insane. Put an arab on a jew on the mountain top in maryland and ask them to make peace, what was i thinking . Reporter reliving the raw emotion of it again, the carters cried and embraced the actors who brought it back to life. His eyes were red. He clearly had been crying. President carter handed rosalyn a hankie, a tissue. She was crying too. She was very moved. She took my hand and said you were a wonderful jimmy. That was about the best thing anybody could have said. Reporter the middle east is still torn by war but the camp david treaty remains unbroken. Andrea mitchell, nbc news, washington. That is our broadcast on a friday night and for this week. Thank you for being here with us. Im brian williams. Lester holt will be here with you this weekend. We of course hope to see you right back here on monday night. In the meantime, have a good weekend. Good night. Right now at 6 00 business is booming in the south bay and its more than just tech. Thanks for joining us. Im kris sanchez in for Jessica Aguirre tonight. Im raj mathai. Bigtime job growth. Something else is booming in the silicon valley. Our business and tech reporter scott budman joins us from downtown san jose, scott . Reporter good evening, raj. A Strong Economy brings new jobs and new money. Thats good news for a slew of new restaurants opening here in downtown san jose. You can call this the new south bay food boom. The south bay has been in a construction boom for a few years. Were building a 23story high rise in downtown. Reporter bringing new jobs and New Buildings and growth in the Tech Industry lasted longer bringing with it even more jobs. But here is food for thought, the south bay is now a hot spot for restaurant growth as dozens of new places to eat like dakine have hit the downtown to shake things up. We feel that there is a void going on here, and i think san jose would be a good spot for us. Reporter lots of food to feet all those tech workers and soon to be new residents. I think in alignment with what the city is trying