CNN  — 

An off-duty Atlanta police officer was involved in a shooting outside a nightclub that left one man dead and two injured Sunday morning, police say.

The shooting happened around 4 a.m. near the entrance of the club downtown after a dispute between a patron and a security guard, Atlanta Police Spokesman Officer Steve Avery said.

The officer, who was working an extra job outside the club, responded after “the dispute escalated” and shots were fired, according to Avery.

The officer fired his weapon, Avery said.

“It is not clear at this point who shot whom, but three people were shot in the incident. One person was pronounced dead at the scene, one person was taken to the hospital in serious condition but expected to survive, and one person suffered a minor injury. The officer was not injured,” said Avery.

In keeping with normal procedure, the Georgia Bureau of Investigation (GBI) was notified and will lead the investigation into the incident, Avery said.

The GBI later identified the men who were shot.

“Frederick Demor Asberry, 25, of Douglasville, was shot and killed,” the GBI said in a release. An autopsy will be performed by the Fulton County Medical Examiner’s Office, it said.

Byron Heron, 33, and Andrew Smith, 30, were taken to a hospital. Heron was in critical condition, the GBI said, and Smith was treated and released.

“Several firearms were recovered at the scene. It is unknown at this time which weapons are associated with the gunshot wounds of the three victims,” GBI said.

The GBI has not named the officer involved.