1) Swift decisive exit.

2) Wait, then exit.

3) Wait and watch.

4) Swift decisive action.

If you are alone your obligation to your family is to leave at once. (Tactic 1: Swift decisive exit.)   If you are with your family maybe your best tactic would be to first send them to safety while you cover their exit, then leave. (Tactic 2: Wait, then exit.)   If after you have gotten your family out safely the situation changes and getting up would draw a dangerous level of attention to yourself maybe your best (temporary) tactic would be stay and remain an invisible face in the crowd. (Tactic 3: Wait and watch.)  Finally, if despite all your efforts the problem is about to erupt and engulf you, then it may be time to act. (Tactic 4: Swift decisive action.)