More than two-thirds of the nation's elementary and public schools are conducting drills to ensure that students, teachers and staff know how to react if there's an active shooter on campus.

That's the finding of a recent report by the Government Accountability Office.

School psychologists warn that there has to be a balance between preparedness and inciting fear in students.

At Forest Dale Elementary School in Carmel, Indiana, teachers and students are told right off that the exercise is a drill. In a recent one, principal Deanna Pitman played the role of intruder.

Active shooter drills are becoming more routine in schools after a rash of school shootings.

The FBI says that between 2000 and 2013, there were 25 shootings in elementary and secondary schools resulting in 57 deaths.