SAN BERNARDINO, Calif. — Classes were canceled at Cal State San Bernardino Wednesday evening after reports of shots fired on the campus.

Shortly before 6 p.m., the university tweeted that there were reports of shots fired near the Visual Arts Building and Parking Structure West and advised people to shelter in place and not try to leave campus.

A short time later, San Bernardino Police Department Lt. Mike Madden told KTLA there was no active shooter on campus, and that investigators were not sure whether shots were fired. The outside of a building had a single strike, but it was unclear whether it was a gunshot, he said. The object, Madden added, could have come from the hillside above the campus.

Later, investigators found evidence that a building’s window had been struck by a bullet, according to KTLA. It was not immediately clear which one, but authorities were focused on the Visual Arts Building and Parking Structure West; earlier, the university had indicated that was the general area where the apparent shots had been heard.

No injuries have been reported, Madden said.

The shelter-in-place order remained in place for several hours. Police were going to each building to escort people out, according to the university. It was not clear when all buildings would be cleared.

All classes were canceled Wednesday night as police investigated.