And stronger than ive been before love and resilience. Ariana grande returning to manchester for a mega benefit concert, raising spirits and millions for those affected by her concerts terror attack. The moment that brought ariana to tears. But first, the nightline 5. Number 1 in just 60 seconds. Good evening. Thanks for joining us. Tonight, dramatic new stories of heroism emerging from surveillance videos of the London Bridge terror attack. As were learning disturbing details about the suspects, one of them a known isis supporter and mev an extremist group. Tonight we meet members of that group who describe their quest to bring sharia law to the uk and the world. Heres abcs eva pilgrim. Reporter it was 18 minutes of terror on a saturday night. Come on reporter pedestrians mowed down on a London Bridge. Leave the area reporter people fleeing the long knives of attackers. Running for their lives. Get away reporter as shots rang out. [ gunfire ] theres shooting. Im trying to keep ourselves safe. Reporter thats right. It happened again. Stay as calm as you can. Reporter terror striking the heart of the United Kingdom for the third time since march. Isis has claimed responsibility for the weekend attack that took seven lives and left dozens injured. Today London Police identifying two of the three suspects as 27yearold Khuram Shazad butt, a british citizen born in pakistan, and 30yearold rachid redouane, of libyan or moroccan descent. Among those killed Chrissy Archibald and londoner james mcmullen, leaving griefstricken families. While our pain will never diminish it is important for us to all carry on with our lives in direct opposition to those who would try to destroy us. Reporter that sentiment at the core of this nations spirit and in their motto, keep calm and carry on, a defiance echoed by londons mayor, sadiq sadiq q with a 234068 perspective. As a proud and patriotic british muslim i say this. You do not commit these disgusting acts in my name. Reporter saturdays attack happened just hours before a massive benefit for the victims of the Manchester Concert bombing. It all started just before 10 00 p. M. A white van heading south on London Bridge suddenly swerved off the road, running down pedestrians, leaving them broken and bloodied on the pavement. The van drove on toward the crowded borough market. Were in lockdown because theres just been an attack. Reporter three men armed with long knives jumped out of the van and began stabbing and slashing innocent bystanders. Take it with me. They were there to do one thing only, to kill people, stab them, stab them to death. Reporter tonight, newly released Security Camera footage revealing the traumatic moments up close. A restaurant manager hustles people inside. The attackers approach, trying to enter. A terrifying tug of war begins as the manager guards the doorway and forces the door shut just as one of the machetewielding attackers tries to get inside. Meanwhile, police were swarming the scenes. Then, gunfire. Oh, my god reporter the attackers gunned down by police within eight minutes of the first 911 call. [ gunfire ] mark kinshoe was out with his friends when he heard that barrage of gunfire, and took cover under a table. It was like 70 or 80 people probably squeezed into the back of the pub. Reporter the slain suspects wearing what appears to be fake suicide vests. Prime minister theresa may taking a strong stance in the wake of the attack. We cannot go on as we are. Enough is enough. Reporter last night President Trump made his first televised remarks on saturdays events. This bloodshed must end. This bloodshed will end. Reporter today an enormous crowd gathering at the base of London Bridge. That concludes the minute silence. Reporter but while the city mourns, some are asking serious questions about why saturdays attackers, at least one of whom was known to police, werent under closer surveillance. We always ask ourselves, well, should we have known, could this have been prevented . Reporter just last year 27yearold khuram butt had appeared in a british tv doc called the jihadists next door. Someone had an isislooking flag on them. Whats an isis flag . Reporter hes seen in intense confrontations with police officers. What are you touching him for . Reporter today british counterterrorism authorities saying butt was on their radar in 2015 but there was no evidence he was planning an attack. There have been 13 or 14 plots that have been foiled in the last 12 months. I mean, what this is telling us, weve probably got to be prepared for more. Reporter with more than 3,000 potential terrorists on British Intelligence watch lists, experts say authorities simply cannot track every single individual. We dont want to live in a police state. We dont want to follow everyone around. That would be impossible in any case. So all the time the Security Services are having to balance risks versus liberty. Reporter in east London Police today continued to search the attackers homes to learn everything they can about the plot. Neighbors tell us one of the attackers lived at this residence and he was well known in the community for having radical views. Neighbors tell us khuram butt was married with a newborn baby. He met me once and he said pray and get close to god. Reporter other neighbors said they called police to report the threats butt was making against nonmuslims. And he said in the name of allah we believe. Im even ready if i have to even, to kill my own mother, if she comes against maallah. Reporter abc news has learned butt was once a member of al muhajiroun, a radical group led by notorious muslim hate preacher amjan chowed ari. Nice to meet you. Reporter my colleague lama hasan met choudary and his followers in 2013. The last hour wont come until a group of muslims rise and conquer the white house. Reporter among them british convert abu rumaisa who fled to syria after being arrested for encouraging terrorism. Some terrorism experts now think he is the masked man in this isis recruitment video. And we will continue to wage jihad. Break borders. And one day invade your land. Reporter in 2013 the group became infamous for socalled sharia patrols. Islam is here in london. Reporter these cell phone videos show young muslim men confronting nonmuslims in the streets of london. Remove yourself away from the mosque. Reporter commanding them to obey islamic laws. Why are you bothering me . Im not because youre walking in a islam area. Just like a fag, mate. Harassing people they thought to be gay. Youre dirty, mate. Is that what you do in your sharia patrols . We havent gone on that particular patrol but im not going it condemn that. Youre not . Im not going to but its none of your business. Of course its my business. As a muslim im living in this society and if i see something wrong happening i need to forbid it. Reporter the group agreed to allow our lama hasan to follow them on a patrol led by rumaisa. How far are you willing to go to get sharia law across the world . Would you use violent means for example . You never know. In the future what lies ahead. But youre not answering my question. To what extent would you go to to get what you want . The jihadi is not a bad thing. It is a noble aim. When the sharia is established, i think that will be the beginning of the end of the United States of america, of britain, of europe, and the entire world which is currently being governed by manmade law. Reporter not only did they not condemn violence the group was actively searching the streets for young people willing to convert to islam. I believe. I believe. That nothing. That nothing. Has the right. Has the right. To be worshiped. To be worshiped. Except allah. Except allah. Allahu akbar. Feels good to do what ive just done really, being a part of something. Muslim. Muslim first. Muslim second. Muslim last. Reporter hasans report insight into the inner working of a radical group. The muslims we spoke to in east london today were horrified by the attack including a Community Leader at a local mosque who asked we obscure his face for security reasons. The first thing i thought was i hope its not a muslim. How does Something Like that, terrorists acting that way, affect your community here . To be honest, we feel our community is under siege because every time Something Like this happens we feel that we need to come out and say its not us. Were appalled and traumatized by it as much as anybody else. Is there a way for you guys to see that there might be this type of behavior brewing . Thats really difficult for anybody to see. Thats difficult for a community to see. Its difficult for Law Enforcement to see. Because if it was that easy wed all see it. This is our city. Reporter at a vigil in london earlier this evening messages of unity and love. We see these men with all these tshirts saying i am muslim, ask me anything. We need to do more of that. As a community we need to come out, be here, show people were humans. Weve got to recognize some people want to divide our community. Some people thrive on fueling division. Thats not me. Thats not the london that i know. Reporter for nightline im eva pilgrim in london. Our thanks to eva for that report. Coming up next, bachelorette Rachel Lindsay gets real about being the shows first africanamerican star. You love them together, but youve never had em quite like this. At red lobsters lobster shrimp summerfest, the lobster and shrimp you love are teaming up in so many new ways. 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Heres abcs nick watt. Reporter Rachel Lindsay is the oldest bachelorette ever. I am. Im old in this world. Reporter practicing lawyer. Smart. Together. I actually didnt say yes at all at first. I really wanted to think about it. For you to have multiple relationships with multiple men in such a public way. Yeah, its weird. Yeah. Its not normal. Ill give you that. It is weird. I still dont understand why she did the show in the first place. I dont. I mean because she has everything in life except the love of her life. And thats where we come in. [ laughter ] damn you skeptic, nick watt. Reporter she was revealed as the bachelorette while she was still vying for nick vialls attention will you accept this rose . Reporter on the last cycle of the bachelor. And the bachelorette started during the after the final rose of the bachelor. Fellas, come on out. Reporter and yes, rachel is the first africanamerican bachelor or bachelorette in this the 34th cycle of the shows. Theres absolutely pressure. Being the first. I mean, that was part of my hesitation in saying yes to being the bachelorette. Its not lost on me that shes the first africanamerican bachelor or bachelorette. Shes the star of the show. I get that. And its important. But at the end of the day i hope that everyones just in love with rachel. Im honored to represent myself as a black woman to america, whos just trying to find love like anyone else. And why not represent myself as a black woman in a positive way . Even if it is on a reality tv show. Reporter earlier this evening big dramatic repercussions. Karmas a bitch, isnt it, demario . Reporter part two of demarios actual and current girlfriend showing up, crashing the group date. All right, boys. Give him some space. Hes one of those guys that has two families. Thats not my type of guy. Reporter demario its just not here right now. Reporter booted. Thank you. That was not on his application form. No. Surprisingly, demario did not disclose the fact that he had a girlfriend, had been living with her and had been intimate with her right up until the time apparently it was like right when he was on the plane. Reporter this season is breaking the mold. Tonight we had horseback riding on rodeo drive. Mud wrestling. And it is about me reporter just a little bit of fighting. This guy whaaabooom reporter also booted. I dont know why they let him on the show. Thats a good question. If youre not drinking a box of wine and throwing stuff at the tv youre not playing along correctly. Reporter she does find love. We know this already. Rachels engaged. Im getting married. God, its a weird show. Im so going to make a believer out of you. My fiance makes me feel amazing. Reporter but who is he . Here are the clues to the final two. Typically, i have found that i run away from the guy who has it all together, that i always run towards the one thats a little bit more challenging. So here i am left with two guys faced with this exact same situation. But when it came down to it, i was really only in love with one of them. Reporter we tagged along the night of that basketball date while rachel was inside dealing with demario and his girlfriend. We never broke up. I dont mean to interrupt you guys. But if i can borrow demario for a second. Reporter i was outside interviewing contenders. That first night is absolutely crazy. You cannot prepare for that. You are just running on pure adrenaline. Tesg. Steron probably a lot of protein powder flowing. Reporter okay. So after tonight 18 dudes still left in the game. Who are the real contenders . Well, theres bryan. Hot and heavy out of the gate. I didnt want to kiss anyone the first night. Next thing you know shes having her face sucked off by bryan. It was a good kiss. Reporter dean, who made that weird comment. Im ready to go black. And im never going to go back. [ cheers and applause ] reporter okay. So who did she like First Impression . From the first night. You know who i liked was peter. Im actually from wisconsin. He was very nervous. And i appreciated that because i was nervous too. I know everybody likes chocolate. You dont like chocolate in. As a heterosexual man i found him the bestlooking. Okay. Peters very handsome. Josiah . At one point i did notice her giving you the glad eye. She did. We made eye contact. And she was smiling because she saw when i hit that three. Reporter he is an attorney like rachel. I think he has a leg up on everybody. He feels he does anyway. You saw that when she looked at me when i made that three. You mentioned that already. I have to keep bringing that up. Reporter behind your back hes talking a big game. Yeah. I would say hes definitely flirting on the line of being cocky, which i dont like cocky. But i do appreciate confidence. Soon as you were announced there was this pressure. Well, she better pick an africanamerican guy. Oh, yeah. Im getting pressure from everyone. You know, am i too black, am i not black enough. I have to be selfish and make this decision for me. But id be lying to you if i tell you i dont think about it. Reporter nick watt for nightline in los angeles. And of course you can see the bachelorette right here on abc. Up next, Ariana Grande with a concert for healing in manchester. Joined by a cavalcade of major music stars. Boost. Its about moving forward, not back. Its looking up, not down. Its being in motion. In body, in spirit, in the now. Boost® high protein its intelligent nutrition with 15 grams of protein and 26 vitamins and minerals. For when you need a little extra. Boost® the number one high protein complete nutritional drink. Be up for it breathe easier with your vicks vaporub. Soothing cough relief that starts working instantly. Ive gotta hit the loo. We cant stay here why . Terrible toilet paper ill never get clean way ahead of you, big daddy. Aww. avo charmin ultra strong. 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Grande briefly speaking about meeting the mother of 15yearold olivia campbell, who was killed in the attack. She said that crying because olivier wouldnt have wanted me to cry. And then she told me olivia would have wanted to hear the hits. Reporter and then came the hits from pharrell and miley cyrus performing happy, love was clearly the theme of the night. What happiness is to you were protected by all this love. And nothing can kind of come through our walls of union. Reporter katy perry wearing a tribute to the victims pictured on her dress. Grande closing out the show fighting back tears with an emotional performance of somewhere over the rainbow. Over the rainbow for nightline im lama hasan in manchester. Thanks for watching abc news. And as always, were online at abcnews. Com. And our Nightline Facebook page. Good night, america