Safe zone logic: Player can enter, enemies can’t; pause inside, chase on exit

You can use a global variable SafeZone. Set it to true (or 1) when the player enters the safe zone, stop all enemies. Set the variable to false (or 0) on exit. In all enemy events add a condition checking that the variable is false.

Another option is to put enemy events in a group and disable that group when the player is in the safe zone.