Open classroom, what do they do for active shooter?

I know it's a morbid question but my childs school has these open classrooms like one huge room with borders to each classroom not a real room with a door. It's like a big space and the tips are all open. I don't understand how this works for active shooter situations. We will be touring next week and I will be asking but I'm nervous to send him to this type of environment for safety and because I don't understand how all the noise isn't distracting.

Looks like this

Also we can only go to the school in our district and you can not move schools unless your child has a disability that is effecting their learning in this environment like if he was deaf was the example they gave me because it's a noisier environment they could move him to another school but that's the only reasons we could change schools so we are stuck here.