WEST COVINA — Authorities placed West Covina High School on lockdown Friday after bullets were discovered in a boys’ bathroom.

The bullets — six rounds of .22-caliber ammunition — were discovered by a student just after 10 a.m., West Covina police Lt. Tommy Garcia said.

Officials placed the school on lockdown as police interviewed students and investigated where the bullets came from, and whether there was an accompanying gun on campus, the lieutenant said.

Ultimately, police found no gun at the school and were unable to determine how the bullets ended up on the campus, 1609 E. Cameron Ave., Garcia said.

By noon, campus activity had resumed normalcy, officials said.