BETHLEHEM, Pa. -

Dozens of police officers descended on Bethlehem's Liberty High School Tuesday morning, but luckily, it was all just a drill.

Officers from 8 municipalities gathered at Liberty at 9:30 a.m. to simulate a lock down.

Once the students were safely in their classrooms, K-9 officers were brought in to search lockers for narcotics.

Bethlehem Police say the search didn't turn up any drugs, and the lock down was successful.

Officials say these drills are the best way to keep schools safe.

"The only way we can really do it is if we get out there and do it," said Kelly Walbert, Liberty's school resource officer. "We practice it and we bring in different police departments and we bring administrators and the teachers and the students and we all participate actively and get it done. And that's what we did today."