A man was in critical condition late Wednesday, hours after getting dropped off at Grady Memorial Hospital with gunshot wounds, Atlanta police said.

But investigators need information on who shot the man and where, and are hoping to find a possible witness caught on a hospital surveillance camera, Sgt. Greg Lyon said.

The possible witness was seen outside the hospital at the same time the injured man arrived, around 4 a.m., Lyon said. Police are asking for the public’s help to identify a man, seen wearing pants with what appears to be an American flag on the left leg.

Anyone with information on the shooting or the man’s identity is asked to contact investigators at 404-546-4235 or Crime Stoppers at 404-577-8477.