The man, whom police are still working to identify, approached the band of 52 Peoria High School students who were practicing in a field at Emmanuel Pines Camp last Thursday, The Arizona Republic reported.
The gunman yelled at the students to "stop making noise. Morning and afternoon is OK, but nighttime is not," deputies said.
Throughout the incident, the man was waving the gun and pointing it at students and staff, deputies said,
Deputies put the camp on lockdown as they searched for the suspect. They were unable to locate him, but believe he lives within earshot of the band camp practices.