South Butler School District security along with state police are investigating a written bomb threat that was discovered Wednesday at Knoch High School. Both the high school and middle school were evacuated.

JEFFERSON TWP — Authorities found no explosives in Knoch High School after a written bomb threat was discovered Wednesday morning.

The building housing the high school and middle school was evacuated before the search was conducted.

At the request of state police, K-9 units with bomb-sniffing dogs from Middlesex Township and Pittsburgh police searched the building off Dinnerbell Road for roughly 90 minutes.

“They didn't find anything,” said state Trooper Ron Kesten.

South Butler Superintendent Dave Zupsic said a student found the threat written on a bathroom stall in the high school.

“It was general, no specific times or dates,” Zupsic said.

He said the student told a custodian who was in the vicinity about the threat.

The custodian notified high school Principal Todd Trofimuk, who alerted school district police and Zupsic.

Students from both schools were evacuated to other district buildings between 10:30 and 10:45 a.m. and were subsequently dismissed.

“As a precaution, we had evening activities canceled,” Zupsic said. He said the district opted to not contact Butler County Emergency Services to have fire and ambulance services dispatched. Zupsic said the district evaluates each situation to determine if 911 services are required.

Trooper Joshua Black said state police also decide whether to call the county on a case-by-case basis.

“Dependent on the situation,” Black said.

The district determined there was no threat to other buildings, so classes in those schools were not interrupted.

Zupsic talked about the evacuation at the school board meeting Wednesday night.

He praised district staff for their handling of the situation.

“So many people were willing to help and were doing what they could to ensure the safety of all of our students, the safety of each other,” Zupsic said.

The investigation into the bomb threat continues. The district is asking anyone with any information to contact school police at 724-352-1700, Ext. 5700.

Zupsic said the only impact on classes today would be the weather. District schools were on a two-hour delay today due to the bitter temperatures.

Tracy Geibel, Eagle correspondent, contributed to this report.