BOZEMAN (AP) — Police locked down Montana State University for about two hours Wednesday after receiving a report that two men were carrying a rifle on campus.

A text alert sent by the university at 9:03 a.m. told people to stay inside and lock their doors while FBI agents, police and Gallatin County sheriff’s deputies searched the buildings and grounds of the Bozeman campus, university spokesman Tracy Ellig said.

Officials lifted the lockdown order at 10:59 a.m.

“We didn’t find anyone matching that description, so we told the campus community to go back to their regular activities, but to remain alert and vigilant,” Ellig told The Associated Press. “We believe there’s no immediate threat or compelling reason to keep the campus on lockdown.”

Students are allowed to keep firearms in designated locked facilities on campus, and officials believe a student may have retrieved a rifle from one of those facilities as he was checking out for the end of the semester, Ellig said.

Police received a call around 8:20 a.m. from a person who saw two men crossing a street and heading toward the center of the Centennial Mall on campus with a rifle.

One man was wearing a hunter’s orange hoodie and the other a green or gray jacket and a baseball hat, the university alert said.

Two men matching the description were briefly detained, but they were released after a search of their car turned up nothing, Ellig said.

“The concern level is low,” but university officials are asking people on campus to be on the lookout just in case, Ellig said.

“If you look in the history of things like this, there have been instances where there was an initial report but it was many, many hours later when something happened,” he said.

University police officers were to beef up their patrols of the campus Wednesday, he said.