A gunman sexually assaulted a 15-year-old girl early Saturday morning in a Southeast Washington alley, D.C. police said Monday.

The teen told police she was walking in the 3200 block of Wheeler Road about 6:15 a.m., when a man forced her into the alley at gunpoint and sexually assaulted her, officials said.

Police described the suspect as a black male with a medium complexion, tall and stocky build, who wore all black clothing. He reportedly drove from the scene in a dark blue, four-door car, authorities said.