Can Raider Attacks occur while you are not in the game?

I have some soldier class dwellers that have great weapons and stats, but I could obviously use them in other rooms.

But if attacks can occur while I'm not in the game, I need them to be at the Vault Door to ward off attackers.

So I'm curious if anyone knows if attacks can happen while you're not there.

Thanks!

No, raider attacks can not occur while you do not have the app in the foreground.

No incidents occur while the app is closed. Only three things can happen while in the background:

1. Resources will continue to be consumed for a short while after moving to the background
2. Timers for production, child birth, and S.P.E.C.I.A.L. leveling will run to completion.
3. Wasteland explorers keep on exploring (and looting and getting damage).