GERMANTOWN, Wis. (AP) — Police officers in suburban Milwaukee have killed a person who fired at them from a middle school roof.

Dozens of students were in the building during the exchange of gunfire but none were hurt, officials said.

Officers with the Germantown Police Department responded around 6:30 p.m. Monday to a person acting erratically in Kennedy Middle School’s parking lot, the Wisconsin Department of Justice said in a statement. When officers arrived the person climbed onto the school’s roof and fired at them.

Three officers returned fire, killing the person, the statement said. As many as 70 students were in the school, which went into a lockdown. The students were later bused to an elementary school where they were reunited with family.

“This is believed to be an isolated incident,” the Justice Department statement said, adding that there’s no danger to the public. “All interactions with the subject occurred outside of the building.”

The school district canceled all classes on Tuesday. The three officers who fired their weapons have been placed on administrative leave as per department policy.

The Justice Department is leading the investigation into the incident. Asked for the shooter’s gender and age Tuesday morning, department spokesperson Gillian Drummond declined to release any further information.