i quickly want to go to our terrorism analyst paul cruickshank. he's joining us from london right now. paul, witnesses say the police are considering this as a possible act of terror. could this fit into the pattern of other vehicle attacks we've seen, especially in europe? >> well, wolf, if this is a terrorist attack in new york city, it would be the first fatal terrorist attack in new york city since 9/11, something that the nypd has been preparing for every day. since then they've been very concerned about vehicle attacks, given that m.o. has been used so much here in europe, in the united kingdom a couple of times. also in nice, france, berlin and also even in the united states. we saw that vehicle attack at ohio state university some time back. it's very, very hard to protect against because all you need is a driver's license and access to some kind of vehicle. and as we saw in nice, where 86 people were killed, it can be very, very deadly, indeed. so isis have been constantly encouraging their supporters in the west, in the united states to l