Transcript for 3 dead, at least 29 hospitalized in UK terror incident

And there you see officials from the metropolitan police department Scotland Yard there updating the public on the latest on going investigation after an apparent. Terror attack in. In London I am ominous odds here in New York we're bringing you the latest on what we know. Practices in that's still unfolding details are still emerging but it looks like officials they are trying their best to keep the public updated. Act incremental evidence does come after we learned earlier when they spoke there wasn't a law firm in terms of numbers dead or injured you saw the official there. Updating people to be able to say that there are four confirmed. Dead from the attack. And involved a car ramming into the gates near Westminster. Houses of Parliament there. One he confirmed what the police officer who was in the line of duty there protecting the house of parliament. And another they believe was the actual attack or the assailant. Himself not a lot of more and we will stay with you right here as the details come out. And a little bit murky there on the other two confirmed dead please official there said he believes that those two people were also among those who were injured and later died as a result of their injuries on Westminster bridge but we will seek. Confirmation. On that is still very much and on an ongoing investigation stay with us here when it take us live now to the scene at eight Molly hunter remains with us there she is being as close as she could get. To the scene of the incident since it broke Molly a puberty tells coming out here in their midst. Quite a number of questions remain. A lot of questions on and we're now about four hours almost four hours after the attack. And they thought very few details about casualties they did say at least three victims including a police officer four total people that. I'm an at least twenty people injured but again he wasn't exactly specific about why those people. Were injured on the bridge were injured in the later stabbing and shooting exchange back here behind eat where you see it's still an active. Crying scene and the message was the saint the public if you had information if you sign anything and have not spoken to police. Please come forward because clearly they're still piecing together information. Four hours later they did say has people had pumped to work. It shouldn't be nervous but should remain vigilant they will see. At more police officers armed police officers out on the streets tonight and he did say on the quote that we've heard. From officials Oliver year for the last couple years this is it daily and for what we thought would never happened out. Every eyewitness that we've spoken with said that police arrived on the scene instantly they were ready the report here at they were heavily armed. But of course this is a situation no police commissioner and no city at wants to deal it on the. My that's absolutely writing as you mention that that resonates with so many people in major urban areas across the world I think that this is something. You anticipate could happen it is not an if but a when. And you hope that the officials there are responsive and prepared as he seemed to have been. There in Britain but I'm street you think you spoke to some folks on the ground there have you been able to get any more sense of what exactly happened or what people. Believe happened what they may have seen or heard on the ground right there because officials understandably are still being very. For cautious with what information they officially release. We did we spoke to two Americans actually you at eyewitness this from Connecticut who. I came out of the cute station but they caught the subway station. And nears. Seconds after that car. I hit the gates said they arrived at and they described the moment that they became it they came up on top of the ground and with absolute chaos they didn't hear any shots. But based on that car rammed into the gates. But they looked around they describe the moment as police officers with heavy machine gun rushed past Andy patterns absolute cap and they sheltered behind concrete. I'm Collins and we asked them. If they were scared in the moment what they're for Stockton if they. I've responded as you might hope that you might respond. In a situation like this evading every one. And especially after last year's watching incidents like this in Europe has thought about how they might respond when put a situation like this and beastie people said. They kind of did they they hid behind concrete blocks. Be realized they had to dad there but they described the moment of absolute shock they had no idea what was going on. They had no clue. What if there were more shots if there was an attack on the list if there was if there are additional attackers. And that is hunting actually we did hear from. Assistant commissioner on as well that they believed there was one attacker but they don't know for sure and he did say they were satisfied with information that there was just this one attacker. But that's why of course this investigation is so urgent an ongoing. I'd bet on it needs it was really interesting talking to these Americans. They just described. They didn't even describe kind of absolute fear they described as shock and and they couldn't process quickly after they just aren't sure. What to do except for get on get low and and really get out of sight. I can't imagine what it must have been like for them enters the last thing they expected to happen that as you mentioned there the police saying. Look we we think we are confident that there is just one attacker we don't know for sure out of an abundance of caution we are locking down. The whole area I'm sure people there. Do you understand and let me just clear up because there was a lot of reporting early Aronson some information about. Potentially someone in the river one person with a knife another person behind the wheel of the car. It it's not clear to me how many people were involved it sounds like the person in the car was also the person who wielded the knife. Is that what you got from the official statement there. That's Anderson from the very brief comments that we just lets that you that. One person drove the cars started the attack which was phase one at this I would take maybe three part act rammed. Into people at and rammed into that gate. And then it with him and let it breached security within night to attack the police officer but again it's not clear if there were accomplices. It's not clear if it did that police as if it mastered didn't actually say. That the guy holding a knife was also the driver but that was that was that I got on that front as brief comments. And then he was the one of course. Who with then presumably gunned down just behind me. By police fire but again they weren't specific about exactly. And how he was killed exactly what time he was killed. That we know he is one of those four people that. It's important to clear up some of these details as you mentioned this is very much. Still emerging and still evolving some other pieces of information we're calling together the French prime minister is to pleaded his quote full support. Two injured French students so it we believe that actually the French Foreign Ministry confirmed that there were a few on a school trip if you French students on a school trip to London. And then the woman in the river the person in the river with in reference before. The port authority of London. Has confirmed to ABC news there was that injured woman who was later then pulled safely from the reference that's where some of those reports originated but Molly it's you that it's only these situations before it speaks to. Sort of the chaos of the moment where however small or large scale an attack is there's a lot of information coming out it's important that we holy really report what we know. To be trail. So thank you for staying on top of us a top of it for us out there what what is next now do we know what we hear again from officials. He said it's heredity and he's out take some questions now an N a couple of last questions and he said we'll do more of this later so I expect. And the Matt police have been really kind of vigilant about. Alerting passive kind of new developments in and holding these Gary's not press conference is that they're tweeting. Any new information they do receive so on I as the night goes on our about four. Hours on us after this attack we should be getting more information expect he didn't give an exact time but we'll certainly spam act. If you Molly hunter on top of the latest for us. On the attacks there and London Molly thanks so much. And of course back you can always good abcnews.com. Let's stay right you're gonna continue to bringing that bring you the latest information. As we have it on this evolving story an apparent terror attack on the Houses of Parliament in London stay right here for your latest I'll be back with Easton.

This transcript has been automatically generated and may not be 100% accurate.