You can easily tell where an alarm is by looking for the wires on the wall. They lead to a little black box, AKA the alarm. Plus, as the guy above said, they're in most of the guard houses.
I don't know what level it is in but it is the one were you get the new kind of sniper gun. Anyways you run down into a building and somone sets off the alarm and you have to turn off the alarm, does anybody know were the stupid alarm is. Whenever I follow the compose and get close to the alarm the compose turns around.
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Get up so I can kill you again!
Alarms are in the striped gaurd boxes, and also in each building you go into on a wall near the entrances. Also top of the stairs on the right in one building.