A shooting at a Montreal college on Wednesday that left one dead and 19 injured will no doubt rekindle concerns about school safety.
When shootings come out of nowhere, surprised students who have nowhere to go, and no idea how to escape, can be easy prey.
There are things kids can do to protect themselves the moment the shots ring out.
ABC News Safety Consultant Bob Stuber recently ran a drill with students and staff at an Oklahoma high school.
When Stuber sent mock gunmen into the halls, he found most students panicked, running past obvious exits into classrooms with no windows. The behavior is typical and can lead to tragedy.
Rule 1: Go to a room with a window so you can escape.
"If you go into a classroom that has no windows, which some of those kids did, you're in a dead end," Stuber said.
If you find a window, be prepared to use it -- whether it's open or not.
"You think a computer costs money. It's expensive. But I don't care," Stuber said. "I would tell them you can pick it up and use it. … Throw it out the window. Get out of that room as fast as you can, and go find a hiding place outside."
Rule 2: When you see an exit, use it.
Sounds simple, but many kids ran right past the exits. When you exit, don't pause. Keep running.
Rule 3: When you get into a classroom, lock the door and keep it locked.
In Stuber's drill, one teacher opened the door, when the fake gunman was outside.
Rule 4: Use what's available to escape.
If the only place you can get to is a school bathroom with no windows and no way out, try soap.
"If you rub that on the floor by the door, see how slick that is," Stuber said. "That guy comes through this door, hits that stuff, he's going down, and you can go out."
If the shooter is chasing you, try using a fire extinguisher, Stuber said.
A gunman trying to make his way through a cloud of foam can't see anything.
"That only took me a couple seconds, but that gave me what I needed to get out of here," Stuber said.
Learn about where you are -- whether it be at school or work.
Be prepared to use anything around you and use your instincts.
When Stuber did a second mock drill at the school later in the day, students used his tips.
They didn't panic and were in a safe place or outside in a flash.