Tennessee authorities Tuesday were searching for about 30 teenagers, many of them convicted felons, who escaped from Woodland Hills Youth Development Center in Nashville Monday night. It was the facility's second such security breach in recent months.

The youths, ages 14 to 19, crawled under a fence surrounding the center’s yard at around 11 p.m., shortly after an employee shift change, Rob Johnson, a spokesperson for the Tennessee Department of Children’s Services, told WBIR.

"At about 11 o'clock last night, about 32 youth -- we believe -- got out of their dorms and managed to slip underneath the perimeter fence," he said.

"Staffing is lighter during the overnight hours, and so, presumably, they planned for that, but we don't know quite yet," Johnson continued. "The facility, as I understand, is under control. They've brought in extra staff."

Many of the teens were found during the night after officers searched the area with dogs and a helicopter, reports the New York Times. Nearly 17 of the teens are still on the run and being sought by Tennessee Highway Patrol and local police.

Most of them have at least three felonies on their criminal record, Johnson said, according to CBS.

"Right now, we're focused on finding out what happened, finding out who knows anything, and whether that can help with the search," Johnson said.

This isn't the first time Woodland Hills Development Center has had a security breach. In May, nearly half a dozen teenagers escaped their dorm rooms, but were caught before being able to leave the property.