Knoch School District went into modified lockdown after a potential threat to after-school activities was discovered at 10 a.m. Tuesday.

After-school activities were canceled, according to an email sent to parents at noon. Students left campus immediately following dismissal.

All Butler County Area Vocational-Technical School students were transported home directly from there.

On modified lockdown, no visitors were permitted in any buildings on campus, according to superintendent Dave Foley.

“Every building is locked, classes are going on as normal,” he said earlier.

The District worked collaboratively with Pennsylvania State Police on campus. Foley said troopers collaborated with school police officers to ensure the safety of students getting on buses for transportation home.

“Some parents have called in and come early and taken their students home,” he said prior to dismissal.

According to Trooper Josh Black, public information officer for Butler state police, an active investigation is being pursued at the district. If information becomes available, it will be put out via his Twitter page, @PSPTroopDPIO.