This is a video of a bad guy who took some shots at police and then killed himself. I just want you to focus in his action at 1:44 where the video is cued.
One of the thing I have promoted for a long time is the fact that if you are trapped inside a location during an active shooter situation and your life is not immediately in danger, it is not a bad idea to use your gun to try to escape via a window or locked glass door. You may want to shoot at a downward angle and near the frame to minimize the possibility of an injured bystander, but don’t get too fancy if the shooting is incoming.
If you go somewhere and you do not come up with an escape plan the first minute you are there, you are taking unnecessary chances.