All South Whidbey schools are on a “perimeter lock-out” Thursday after a former student made a threat, officials said.

All doors to the schools except the front main doors are locked, and all visitors must sign in at the main office at each school.

A former student made a threat sometime Thursday morning, said District Superintendent Jo Moccia, and the lock-out was initiated as the school day started.

The lock-out will continue through the day and may also be in place Friday, Moccia said.

Officials did not identify the student who made the threat. The student has not been enrolled since last year.

The Langley Police Department and the Island County Sheriff’s Office are providing security at the schools, and are also searching for the former student.