An armed robbery in a parking lot outside a southwest Atlanta movie theater Thursday night was interrupted by an off-duty police officer who fired his gun at one of three alleged bandits, police said.

The incident occurred at Movies ATL at 3760 Princeton Lakes Parkway S.W. in the Camp Creek Marketplace shopping center, police said.

The off-duty Atlanta police officer, working security at the theater, came outside to discover what investigators described as a robbery in progress: Three men had set upon a motorist in his vehicle in the parking lot.

The suspects struck the victim in the head with a weapon and fired one shot, grazing the victim in the head, Atlanta police spokeswoman Kim Jones told the AJC.

One suspect allegedly pointed a gun at the officer, and the officer fired with his own weapon, police said. The officer missed, and the three suspects ran away.

The off-duty officer chased one of the men toward the rear of a nearby shopping center and was able to place him in to custody, Jones said. He identified that suspect as 28-year-old Paul Hester.

Two other suspects fled in a dark vehicle, Jones said.

Meanwhile, the robbery victim had driven off in his vehicle. He was located by police about a mile away, on Camp Creek Parkway near I-285.

He was taken to Grady Memorial Hospital. His condition was not immediately known.

Staff writer Mike Morris contributed to this article.