let's turn to don berelli, former agent of the fbi. we've got richard engel here as well.tuation we see unfolding in watertown and what strikes you about it. >> well, obviously, what the report said about calming down, calm is good. but certainly calm doesn't mean that this thing is over with. i don't know what that means. i mean, obviously there was a containment of a perimeter, and it seems that that's where they believed the subject to be. several scenarios could be unfolding, that either that person's been taken into custody or they've cleared the perimeter. the search continues. what's key tomorrow is that we still believe there are accomplices, according to reports. so by no means is this area out of the woods in terms of being a dangerous situation. >> that reminds me, there's a cambridge, massachusetts, location where two people we reported were taken into custody this morning. we did not say they were taken under arrest, and there is a distinction. they may be somebody just being interviewed by police in connection to possibly knowing these two men. let's turn to

. >>> joining me in new york, don berelli who investigated the oklahoma city bombings, u.s. embassy attacks in 1998 and bombing of the "u.s.s. cole" in 2000 in yemen. as you're hearing from pete's ror i reporting, we're learning more about the type of explosive devices used, material used inside, ball bearings, nails to be used as projectiles to create mass damage and mass casualties. does this depict to you from what we've learned and from what your experience kidictates that this would be a work of a foreign terrorist group? >> this has the flavor more of a homegrown type event. i say that, because as pete said, the information on how to make this device, crude, but effective, but it's on the internet. it's readily available to people that don't have formal training. as opposed to what we saw with the attempted subway plot bombing in 2009 with naji bullizazi. a different method. he was making tatp out of hydrogen peroxide. that took a fair amount of training in which we traveled overseas to obtain that training, come back and use it here. that's the only reason i say this