Another What if, bomber situation.

[Pickpocket]

If he is shouting Allah Ackbar or something along the way of that, it is not a good sign.

"Allah-u-Akbar!" (God is Great) isn't something you want to hear someone screaming at the top of their lungs for no apparent reason. If you do, you should probably look for a place to hide the wife and kids kinda quick-like.

However - it's not as though that phrase is a foolproof indicator. It's inscribed upon both the Iraqi and Iranian national flags, and it's often used as an expression of happiness or excitement.
It's spoken aloud during each stage of their prayers, and I've seen relatively benign crowds chant it back to a speaker on cue.

Like I said, it's not perfect - but you don't want to hear it screamed out for no apparent reason. That usually meant our day was about to get a bit more exciting.

[DefensiveCarry.com]

[AirForceShooter]

get me and my loved ones outside and call 911.

AFS