development in the boston marathon bombing investigation. pamela brown with the city's response to the attacks, senior medical correspondent elizabeth coh cohen, but we begin with susan candiotti. we learned overnight from the fbi has one of the two bombs was packed into a pressure cooker. the second was located in some kind of metal container. we don't know if it was a pressure cooker or not. susan, what else do we know knew this morning? >> good morning. these, as you said, are gripping photos taken by those fbi crime seen technicians. in particular, we are talking about a huge blast field that these things were found in. so just amazing work done by these analysts. as they found, for example, twisted debris, pieces of that metal container that the alleged bomber or bombers used to put