BIRMINGHAM, Ala. -- Four people were shot and wounded outside an Alabama bar early Sunday in what police described as an exchange of gunfire.

Birmingham Police Lt. Ron Harless said three men and a woman were shot outside Tin Roof in the city's Lakeview District, AL.com reported.

The shooting was reported around 12:45 a.m. to an off-duty Birmingham police officer who was working inside Tin Roof.

Police and Birmingham Fire and Rescue Service responded and found a man who had been shot and a woman who was grazed by a bullet in the parking lot.

An SUV reportedly fled the scene and was pulled over nearby. Two seriously wounded men, including one with life-threatening injuries, were in the vehicle.

All four gunshot victims were transported to UAB Hospital.

The shooting was under investigation, police said.