Missouri ? Shots were fired during the night on the campus of Northwest Missouri State University during homecoming weekend but no one was injured, school officials in Maryville said Sunday.

No one had been arrested. Officers were looking for two men they described as persons of interest, but said they believed the men had left the campus.

The campuswide alarm system was activated, warning “shooter on campus” over loudspeakers, said university relations vice president Mary Ann Lowary.

Students, faculty and staff were told to go to their rooms and lock their doors as a precaution until officers could check each of the 13 residence halls and the other campus buildings, Lowary said. The lockdown lasted until about 6 a.m. Sunday.

The gunshots were reported late Saturday, shortly before midnight, in a parking lot near The Station, a conference and activity center on campus, a university statement said. Lowary said the building has a 24-hour convenience store and snack bar for students.

Maryville is about 90 miles north of Kansas City.