Editor's Note: A previous version of this story stated the suspect was "arrested." He was taken into police custody but did not face any criminal charges. The correction is reflected in this updated story.
An off-duty police officer was taken into police custody Wednesday after he was seen carrying a gun on a university campus.
The reports of a man with a gun sent American University into an hour-long lockdown.
"In this case, someone saw something and said something," said Camille Lepre, the university's assistant vice president of communication, in a statement.
The sighting on an American University shuttle bus was reported to AU Public Safety, the statement said.
Around 8:00 p.m., American University sent out an emergency alert, telling everyone on campus to "shelter in place."
While the campus was in shelter mode, Metropolitan Police and AU Public Safety investigated the report, the statement said.
And a circulating photo, taken of the suspect on the bus, lead to his ultimate identification as an off-duty police officer.
"American University thanks the entire AU community for their cooperation during this incident," Lepre said. "Every student is safe tonight."
He was arrested, but "no crime was committed," the statement said.