Montana State University officials say a lockdown has been lifted after police found nobody matching the description of two men reported to be carrying a rifle on campus.
Spokesman Tracy Ellig says a sweep of the campus turned up no immediate threat Wednesday morning.
An alert sent by the university says police received a report the men were walking toward the center of campus with a rifle.
Police and FBI agents searched buildings and told people to stay inside and lock their doors.
Ellig says two men matching the description were briefly detained, but they were released after their car was searched.
Students are allowed to keep firearms in locked facilities.
Ellig says officials believe a student may have retrieved a rifle while moving out for the end of the school year.