The accident occurred around 7:30 p.m. Saturday at 52nd and Jefferson streets.
Police say two ATVs collided with a third ATV. The 63-year-old driver of the third ATV was killed at the scene.
A male driver of one of the other ATVs involved in the crash is listed in critical condition at the Hospital of the University of Pennsylvania.
The other ATV driver drove off. His vehicle is described as a red and yellow Banshee ATV.
Police are investigating.