American University was locked down for almost two hours Wednesday night after police received reports of a man with a gun, but the incident was cleared with no injuries and students were told they could resume their normal activities.

As it happened, there was a man with a gun, and by 9:30 p.m., police learned that he is an off-duty D.C. police officer with a permitted weapon, said Officer Hugh Carew, a D.C. police spokesman.

The university locked down its Northwest Washington campus after receiving calls about 7:55 p.m. about a man with a gun on the main campus. The university’s Twitter account posted two tweets alerting students that the campus was on lockdown and told them to “shelter in place.”

Shortly after 8:30 p.m., the campus public safety department tweeted a photo of a man and woman who appeared to be on a shuttle bus.

The campus police added, “If you see either of these ppl, please DO NOT approach,” and urged students to call the public safety department.

Journalists talk to Lt. Jesse Porter of the Metropolitan Police Department. (Michel du Cille/The Washington Post)

Joe Wisniewski, an AU senior and an ANC commissioner for the school’s off-campus apartments, said many students were frightened when officials tweeted a picture of two potential suspects.

“That’s on a whole other level,” Wisniewski said. “People are scared. People are already stressed out about finals; this is the last thing that people expected.”

An AU student saw a man with a holster on his waist as they rode a campus shuttle bus, and she contacted authorities, said D.C. police Lt. Jesse Porter.

Police from the District, the university and the U.S. Secret Service responded to the campus and determined that the man the student saw was an off-duty officer. There was no crime committed and no shooter.

“We train students that if they see something to say something, and that’s what happened tonight,” said Camille Lepre, assistant vice president of communications for the university. “Everyone is safe.”

Get updates on your area delivered via e-mail