Two Chinese men were detained on accusations they spread an earthquake rumor that sent hundreds of girls running from a dormitory, the state-run Xinhua News Agency reported Thursday.

More than 400 students stampeded out of the dorm in northwest Gansu province at 2 a.m. May 15 after getting phone calls warning of a quake within 10 minutes. No one was injured, but the girls stayed on a sports field until authorities persuaded them to go back inside, Xinhua reported.

A police investigation showed the callers were two employees of a property management company who felt bored while on duty, Xinhua reported. They had claimed to be government officials.

Many Chinese have remained nervous since the deadly May 12 quake that killed more than 41,000 people and left about 5 million homeless. Hundreds of aftershocks have been recorded, and many people in the quake zone in neighboring Sichuan province still refuse to sleep indoors.