"I need everyone to leave everything that you have in place – do not take anything out of here except for your bodies – I don’t wanna see any bags, books or anything."
As and after he says this, all the visible attendees gather their belongings before heading to the exit.
Because who doesn't want to leave their $2K+ camera laying around for security goons to mess with. That said, when a potential bomb threat or other security issue has been called just leave the bag and get out of the room - your life isn't worth your belongings (even if 99% of the time stuff like this is just a false alarm).