Bismarck police officers investigated a bomb threat written on a bathroom wall at a middle school Wednesday afternoon.

Sgt. Dwight Offerman said he and three school resource officers were called to Wachter Middle School at 12:45 p.m. Wednesday afternoon, shortly after school officials became aware of the threat.

Offerman said the threat was written on a bathroom wall, but he declined to say whether it was a boys' or girls' bathroom.

School staff did two searches of the school Wednesday, and nothing unusual or suspicious was found, Offerman said. He said the school will be searched again today before students are let into the building. Two school resource officers will be at the school, he said.

Officers were following up on leads to identify a suspect Wednesday afternoon.

"Officers are working diligently right now," he said at 5:35 p.m.

- Jenny Michael