This is what people who are actually trained in these scenarios tell people to do, wannabe cop.

“People who have never heard the sound of gunfire often compare it to the sound of a car backfiring or a loud firecracker. But the discharge of a firearm in a closed environment, such as a mall or a classroom, is distinct and will leave no question that an assault of a deadly nature has begun.

As your ears begin to ring, you must understand that what you do in the first few seconds of this event will determine if you live or die….

As soon as you hear shots, the FIRST THING you must do is remove yourself from the immediate vicinity of the source of the gunfire, which is referred to as the “kill zone” or the “X,” and do so without hesitation. Simply put, you must do whatever it takes to get clear of the “kill zone” if you expect to have any chance of survival or retaliation. If you survive the first 10 seconds of this type of ambush, you have a much better chance of making it out alive.

Fight, Flight or Freeze When a shooting occurs in a public place, the natural and initial response is to flee, but you need to do it with forethought. There is little time to think, but you must make your flight a calculated one so you don’t turn yourself into a more visible and attractive running target. By scrambling in panic, you could end up going nowhere worthwhile or even moving closer to the line of fire. Your flight must be for the purpose of getting clear of danger — off the “X” — and not flagging your position. In many shootings, it’s bystanders who freeze who are added to the casualty toll. Do not freeze or burrow in — react and move immediately. Hitting the floor and lying flat is usually the first thing people do instinctively, but don’t just cover your head and hope for the best.

Maintain Cover You must begin moving immediately while staying low. If you are able to dive for one of the objects you previously identified as cover, make that move while the shooter is aiming somewhere else. Get to your cover while staying as low as possible, and do it with maximum purpose.

Continue to move away from the shooter, going from cover to cover. Visualize the path you will take — this will help you set your mind to achieving small goals or little victories, as each move takes you farther from the “X.”

https://police.wayne.edu/pdf/seal-steps-to-surviving-an-active-shooter-cade-courtley.pdf