Westlake High School parents were informed Thursday of a potential safety threat that prompted increased security at the campus.

The threat was contained in graffiti in a boy’s bathroom stall that was spotted by a student who notified campus administrators this morning, said Claudia McWhorter, director of communications for Eanes ISD. McWhorter would not say what the graffiti depicted, but she said it made a threat to the school on Friday, May 3.

Investigators are trying to determine the culprit, McWhorter said.

In a letter to parents, school and district officials said similar recent threats, including one at Lake Travis ISD last month, were not acted upon.

Even so, school officials announced they will: search and secure all areas of the campus, including classrooms; increase law enforcement patrols around the school overnight Thursday; increase the law enforcement presence on campus on Friday; and keep all doors locked at the high school until 8 a.m. on Friday (early morning students will be able to enter at monitored doors).