Brien McMahaon High School in Norwalk held a lockdown drill on Thursday.

School leaders say they put a big emphasis on preventing a potential school threat. The "see something, hear something, say something" concept is stressed at Brien McMahaon, and the school system allows people to anonymously report concerns. The school also focuses on response to make sure students and staff know what to do if there's a real emergency.

As part of the drill, some classrooms were assigned to evacuate, meeting at a nearby site off campus. School leaders went through what students and staff could expect in a real active-shooter situation.

While some students were outside, others spent the drill barricaded inside their classrooms. They turned off the lights, locked the door, got out of sight of the windows, pulled down the shades and grabbed anything that could help them fight back against a potential shooter.

School leaders say students have actually requested running these types of lockdown drills. They say students are routinely offering up ideas to make sure they're prepared in a worst-case scenario.