How many people can you kill without leaving the room (no windows)?

No windows??? how did 100 people enter there? of course using a door or doors

Now, if I started killing everyone with a knife, other people would notice me and escape through these, so the number of people would decrease.

In the case where all the doors are closed or they do not exist, the number of victims from a knife would be 100, including myself and if there was someone behind the doors, they would be dead too as I would shoot them.

In the case where they are opened, people would start to escape and immediatly call the cops, so I would kill everyone that I could and some cops, but in the endI would be stopped.