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I really can't answer that question. If i heard the shots while walking down the street i'd probably take cover and wait for police. If I was in church and friends and family in other rooms I might try to get to them. I like to play mental "what if" games to try and keep my awareness up. I have worked part time at our church for a few years so i know every part of every room. I could move around and stay covered or at least concealed. Other places that i don't know as well would give me pause.
The OP did specify teachers. I believe in an active shooter scenario, the teacher should get the students to take cover in the corner while they cover the door. Wait for the police/resource officer to track down the shooter. If the teachers go looking for a shooter, they leave their own students vulnerable. The main idea behind arming teachers, IMO, is deterrence. Most shooters prefer targets with no resistance. If they believe that the staff could be armed, even if its just a slight chance, they will probably find another target.