Transcript for Investigation of London subway attack takes surprising turn

Very tense times, thank you. We turn to new developments in that London terror attack. This newly released surveillance footage may show the suspect shortly before that train bombing that injured 30 people on Friday. A second man has already been arrested in connection with the attack. Our chief investigative correspondent Brian Ross is here with more. Good morning, robin. The investigation is taking some surprising turns of great concern this morning. As police in London are investigating whether the bomb that went off in the subway was meant to be something not seen before and perhaps much more dangerous and explosives designed to release deadly chemical gases. This morning the focus is on one of these row houses in the London suburb of sunburr on Thames, the unlikely location of the bomb fact, police believe. It is owned by this elder DI couple. Penelope and Ronald Jones honored by the queenor serving for foster parents from young men including some from Iraq and Syria. An 18-year-old who lived there is under arrest and surveillance footage made public overnight appears to show a young man leaving the home 90 minutes before the attack carrying a white bag which police believe may have contained the bomb that went off in the subway Friday morning. Neighbors were stunned that a foster child might take advantage of the goodness of the elderly couple. He was a lovery young man. You wouldn't suspect anything from him. He was polite, courteous to the old couple. Reporter: On supplement a second young man, 21 years old was arrested nearby. Seen in a video posted by our British tabloid. That second arrest led to another series of police raids at a home disturbingly clothe to heathrow airport. The police have made good progress with what is an ongoing operation. Reporter: Officials say the forensics of the bucket bomb placed on the subway raise new questions about the attack. The absence of any metal suggests to bomb experts that the goal instead may have been to release a deadly chemical. Given the series of four attacks in the past six months the British prime minister told George she wants a hard look at what is being done to prevent them. You said in the wake of the other attack, enough is enough. Things need to change. It's time for even embarrassing conversations. What did you mean by that. Well, it is necessary for us to look as we are doing at whether our police and security services have the full capabilities, the powers that they need. Reporter: One big break in the case is the fact that the suspected bomber was captured alive. Apparently as he tried to flee the country, this morning police will be pushing to learn more about the plot and the bomb, whether it was intended to be a gas attack. So far no chemical residue has been detected. ISIS claiming responsibility. What are officials saying. That's true and want to know if ISIS directed these two young men refugees who came to great Britain as foster children. We have to find new ways on how the knit spreads these ideas, the prime minister said. She is one of many leaders

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