The all clear signal was given around 11 a.m. that it was safe to reenter the building.

By: KDKA-TV News Staff

CANONSBURG, Pa. (KDKA) — A chemical leak prompted the evacuation of Canon-McMillan Senior High School on Wednesday morning.

According to a letter to families from district officials, the chemical gas release was confined to the school’s swimming pool area. It involved liquid chlorine.

About 400 students and staff members were in the building at the time.

The school was evacuated while North Strabane firefighters and Washington County Hazmat checked out the situation.

Both gave the all clear signal around 11 a.m. that it was safe to reenter the building.

At the time of the evacuations, school officials say some of the students were taking the Algebra 1 Keystone test.

In a statement, the principal said, “It was a team effort and we were able to quickly adjust our schedule to minimize any impacts to testing and the majority of students will complete the test today. The handful that were not able to will take the second module at a later date.”

A maintenance man was evaluated at the school by EMS and was transported to a local hospital for further evaluation. His condition is unknown at this time, but an official on the scene said it was more of a precautionary measure and he is expected to be fine.

Stay with KDKA for the latest on this developing story.