FOXBURG, Clarion Co. — Allegheny-Clarion Valley School District students will operate on a 2-hour delay on Tuesday, following an after-hours threat Monday that led to schools being locked down for nearly an hour and all evening activities and practices canceled.

Students will arrive two hours later, but teachers will still report on time, according to one school official.

Superintendent David McDeavitt said Monday a threat was received sometime after schools had dismissed for the day and the lockdown affected those remaining on campus. He said students were dismissed and left school on their buses before the lockdown was initiated.

It was not clear which schools were directly affected by the lockdown, which was lifted about 5:45 p.m.

Another school official said some after-school activities ended abruptly while others continued with restricted access.

McDeavitt said he contacted state police in Clarion and canceled all evening sports and activities in the district.

He did not know how many people were affected by the lockdown or how the threat came in.

State police in Clarion are investigating, but could offer no further information Monday night.