You can never fully prepare for something like that, but soon, schools across Missouri will know what to do in case the unfortunate event happens.
"The more you know upfront, I think the better you'll be in the event if something happens," said Lt. Mike Ceperley, Emergency Coordination at Northwest Missouri State University.
A new state law requires all schools to participate in a yearly active shooter and intruder response drill.
The Missouri School Board Association held a workshop on Thursday in Kansas City to train teachers and law enforcement on how to keep students from panicking in an active shooter situation.
"We have an opportunity to really train our students and drill them in all aspects of responding to a hostile intruder incident," said Northwest Missouri State University Chief of Police Clarence Green.
Green learned communication is key when dealing with a shooter or intruder.
"Make sure that we're communicating with our students, faculty and staff as well as our parents of those individuals," he said.
"One of the things you have to have is an open relationship between the schools and law enforcement so that we can work to stop these things before they occur," said Buchanan County Sheriff's Deputy Sarah Hardin.
Preparing for the unexpected may be tough, but the annual drills are designed to make this kind of scary situation a little easier to handle.
"What we want to do is be able to put those tools into the teacher's boxes so that when they get in those crisis situations they can revert back to their training and start doing the techniques they need to to keep those students alive," said Deputy Hardin.
Those conducting the shooter and intruder drills must be certified.
Teachers also need an annual training.
The drills are set to begin this fall.