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.

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 has not named the officer involved.