Law enforcement officers say they found no evidence of an active shooter and no injuries in their search of a dormitory at the Air Force Academy late Friday night.
Authorities say the academy in Colorado was placed on lockdown at around 10 p.m. MDT, and that text messages were sent to airmen warning them of a possible shooter.
The El Paso County Sheriff's Office said military personnel and law enforcement officers cleared dormitories and knocked on doors but found that there were no injuries or shots fired.
The Gazette in Colorado Springs reported that security forces said they believed the incident took place at the academy's prep school.
Earlier this week the Air Force Academy leader delivered a stern message in a speech to cadets after someone wrote racial slurs on message boards outside the dorm rooms of five black students at the prep school.