Imminent threat to life

If you see an attacker threatening you and he can see you, run.

Run safely and to safety.

If possible, run to the side.

The basic rule of safety is applicable if you can resort to safe flight when a threat is perceived. It is important to stress the word safe. A headlong flight to an unknown destination could make the situation worse. It is essential to determine where I want to go, what route leads there, whether it is safe to take and what the potential risks are.

If I'm on the lower floors and others are fleeing from the threat from the higher floors to the exit below, there's a good chance that I may be able to escape. However, if I am on a floor where I have registered the attacker myself, it is essential to assess whether it is within my power to escape so that I do not become his next target. Escape must not be headlong, but targeted.

Hide in the nearest suitable place, lock and barricade the door if possible.

If the door opens outwards, put heavy furniture or anything solid in front of it and tie the handle to it (with a belt, electric cord,...)

If I'm in a situation where escape is impossible, too risky, or not possible for any other reason, then rule number two comes into play, which encourages hiding. The crucial question is where to hide. If I'm in a building I know, I have a greater awareness of the possibilities than if I'm in a building for the first time.
In a school-type building, it is logical to hide in offices, classrooms, and other rooms that can either be locked directly or barricaded in other ways. People hiding should silence their cell phones and be quiet so that an attacker is not attracted by the sounds outside the door. It is also a good idea to inform the security forces where you are and how many people are there if you have this information. But again, think about your concealment.

If you can't run or hide, prepare any improvised weapon - a fire extinguisher, a coat rack, a sturdy chair...

Stand behind the door/corner and attack with all your strength. Aim for the head.

You have a better chance in a group than alone.

We're getting to a situation where everyone is faced with a crucial choice. If I'm in immediate danger, have no way to escape and nowhere to hide, I have to choose between two bad options. Either I do nothing and very likely die, or I try something and at least have a chance of survival. None of us who have not been directly in this situation can say in advance how we will act in this fatal situation.
Generally, more people have a better chance than one on one. In such a situation, the attacker has the advantage. If the circumstances permit, it is a good idea to take advantage of the element of surprise. Not every active attacker expects any of his victims to resist him. Furniture, tools, or anything that can serve as a makeshift weapon can also be used.