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NPR's national security editor Phil Ewing has been with us all evening, and he's going to give us an update now first on that death toll. I know we've been vague about the numbers. Talk about why.

PHIL EWING, BYLINE: Yea, that's right. French officials in Paris have said they know about 120 people have been killed in this attack, but there are also media reports from Paris that put the number higher - 150 or more. One number that we do not have as well is the number of people who were injured. It could be a lot because of the nature of this attack. And that's a big factor in these terrorist attacks as we remember from Boston, too, where the death toll is relatively small, but the number of people injured by those bombs was quite high.

CORNISH: And reportedly some attackers are dead now, too. Can you talk about those numbers, what we know?

EWING: Yeah, that's right. We know four or five attackers, according to the local reports, have been killed. And the latest word on the cable networks is that some of them were wearing explosive suicide belts. We aren't sure if those were the same ones who we believe attacked the soccer stadium or are separate. But there's also some attackers at large, we believe, with their weapons either trying to escape, or potentially launching follow-on attacks. Right now we just don't know.

CORNISH: Let's talk about a potential investigation, what the first steps might be for investigators based on what we've seen so far.

EWING: Well, it's going to be a huge crime scene just because of the scale of this attack and the complexity, the number of sites in Paris that were involved, the number of attackers that were involved. But one thing that's going to come in handy are the surveillance cameras which blanket Paris just like a lot of modern cities. We remember from the Paris attacks in January on Charlie Hebdo, the newspaper and the kosher supermarket, how critical the surveillance footage was in those cases. In fact, those images of that attack became familiar on TV around the world. So that's going to be an initial thing that investigators look for as well as putting together shell casings from these crime scenes, interviewing witnesses, all the other basic police work you would imagine would go forward from an attack like this.

CORNISH: And to remind people the depth and the scale of this, those attacks back in January, we're talking about less than two dozen people killed - right? - including the attackers. Here, it's just massive.

EWING: It is massive. It's one of the largest, if not the largest terrorist attack in Europe ever and certainly the biggest mass-casualty incident in Paris in a very long time, possibly since World War II.

CORNISH: That's NPR's national security editor Phil Ewing. Phil, thanks so much.

EWING: Thank you. Transcript provided by NPR, Copyright NPR.