A 15-year-old Washington High School student was taken into custody Thursday morning for leaving a threat in a bathroom stall at the school.

Washington police said the handwritten threat was found shortly after 8 a.m. This is the third threat at the school since February.

Authorities said the school was placed on lockout and the Franklin County Sheriff’s Office, the Missouri State Highway Patrol and St. Louis Airport Police responded to the school.

The agencies did a sweep and then assisted with securing the school, according to Washington police.

There was “minimal disruption to students and staff” and an increased officer presence was at the school until noon when students were released.

Police said the suspect was quickly identified and confessed to writing the threat. Juvenile authorities were notified and charges will be sought, police said.

This is the third threat located in a WHS bathroom in less than three months.

In the first two incidents two girls, ages 16 and 14, were arrested for the separate incidents.

Friday was scheduled to be the last day of the 2018-19 school year, however, rising river waters prompted school officials to cancel classes.