Kind of seems a little hectic... not sure it was done on purpose. The rescue workers had just gotten there to remove bodies... so you know lots of eyes on the situation. Then reports of them running into other buildings, grabbing whomever they could as shields.
No, actually, the reports are that the terrorists methodically changed clothing (to civvies) before setting off the explosions. They planned this as a way to escape with their miserable useless murdering lives.