I know I'm going to be in the minority here, but highlighting a person who is probably innocent bothers me. I don't see his reaction as suspicious. He's just witnessed a horrific event, his clothes were nearly blown off his body. I don't think running away is unusual.
http://www.dailymail.co.uk/news/art...el-suggesting-device-WAS-pressure-cooker.html
We all like to think we would be the ones running towards the blast to help. But nobody can predict what their reaction will be in a situation like that. You might freeze. Fight or flight might kick in.
IF this young person is innocent (there IS a chance he's involved, of course) I hope he doesn't feel guilt for running away (and having it plastered all over the news).
There's no judgment from me. Until I've been in that situation - and I pray I never am - I can't say how I'd respond.