The scenario: A shooter gets inside the high school, takes several students hostage and threatens to burn the building to the ground.
"This is life and death," said Grady Shuey, Assistant Fire Chief of the Brownwood Fire Dept, who was on scene with several firefighters Tuesday morning.
The major players: Emergency personnel, from firefighters and police officers to EMTs, all springing into action as the school locks down.
The game plan: The shooter is isolated and 900 students, plus faculty and staff, are shepherded out of the school and into the Church of the Good Shepherd across the street.
It's the first evacuation drill the school has ever done, in an effort to be prepared for the worst.
"It's going to be chaotic regardless, but at least we'll have a little experience on it," said Fred Bastardo, the school resource officer and organizer of the drill.
"I just think we need to be prepared for anything and we want to protect our kids, first and foremost," said Bill Faircloth, principal at Brownwood High.
The drill wasn't as easy as getting kids out of class. School officials say it took about a year to coordinate and while there were a few kinks, some preparation is better than nothing.
As for how seriously the students took it...
"I didn't have to call down a student out of a thousand. Not one student did I have to get onto," said Faircloth.
So it appears everyone involved realizes the training could one day save lives.
School officials hope to continue the drill at least once every year.
Parents were notified ahead of time so no one would panic.