Transcript for New arrests made in deadly London terror attack
Reporter: Good morning, Amy. The focus today on the investigation into the attacker identified as Khalid Masood, British authorities are digging into his lock history of islamist radicalization looking to see if they missed any signs and if family, friends and associates were in on the plot. New images today of the moments of terror in London. You see the chaos and confusion as prime minister Theresa may is hustled to safety from parliament. Her gars with weapons drawn in this video from the "Sun" newspaper. These pictures of the attacker moments after he was taken down by police. This morning we're learning more about him, the man responsible for this deadly terror attack in the heart of London. Authorities say 52-year-old Khalid Masood was a British citizen born Adrian russelajoa living in Birmingham where investigators are seen collecting evidence. Masood had been investigated for ties to violent islamic extremism a decade ago after his conversion. In 2003 they concluded he posed a low risk. ISIS now calling him a soldier. Overnight thousands gathering in London's trafalgar square to pay tribute to the victims. And the death toll is rising. A 75-year-old man succumbing to his injuries. So now four killed in the attack. Over 40 injured from 11 different countries. Among the deceased veteran police officer Keith palmer who gave his life protecting parliament. This might be the last image of him taken with a U.S. Tourist just moments before he was stabbed by the attacker. And an American, Kurt Cochran of Utah, 54, a musician visiting London with his wife Melissa celebrating their 25th wedding anniversary. The only word I could really describe it as is surreal. He did live his dream and not a lot of people get to do that. Reporter: The roads are open again, parliament is back in business. London is back defiantly. Amy. Terry, authorities have said Masood acted as a lone wolf. But if that's the case why so many other arests in this? Reporter: That's an excellent question, Amy. There have been eight arests so far. Two of them last night that authorities have said are significant. It does seem the more that they dig into his associates the more they are finding perhaps more involved in the plot. Terry Moran, thanks. Back here at home we have
This transcript has been automatically generated and may not be 100% accurate.