Students and staff at Washington Middle School were evacuated for several hours Tuesday morning after someone wrote a threat on a wall at the school, but everyone is now safely back in the building after the St. Louis County Police Department gave the all-clear.

The Mehlville School District said that a message was found on a wall at the school early this morning that said “I’m going to blow up the school.”

Assistant Superintendent-Supervision of Schools Jeff Bresler wrote in an email to the middle school’s parents sent at 11:35 a.m. Tuesday, “We take all threats seriously, and this triggered an immediate evacuation. So far police have not found any weapons or explosives on our campus.”

Students were evacuated about 10:30 a.m., the district said.

The district continued to follow its emergency procedures and told parents they would be informed when students returned to the school.

While students waited safely outside, police conducted a “thorough” sweep of the building, Bresler said.

“Students are safe and cooperative as they wait for the all clear,” Bresler wrote.

An hour later, at 12:36 p.m., Bresler sent another email to parents to let them know that police had given the all-clear and students were returning to the building.

“They have indicated it is safe for students and staff to return to Washington Middle School,” Bresler said in the followup message. “Our priority for the remainder of the day will be easing back into instruction while also checking in with our students and helping them process this morning’s events.”

Lunch will be served on a modified schedule, Bresler noted.

While students were waiting outside, they were grouped by classroom and were outside with their teachers in the space between WMS and Trautwein Elementary next door. If students needed to use the restroom during the evacuation, they were able to go inside Trautwein.

“I want to thank the staff at Washington Middle School. They responded to this threat swiftly and calmly and put our emergency procedures into action,” Bresler wrote. “Also thank you to our staff at neighboring Trautwein Elementary School who provided support to our WMS students while they were evacuated. I also want to thank our students for their cooperation and patience. Finally, thank you to St. Louis County Police for their thorough investigation of our school.”