Four people were shot - one critically wounded - in Southwest Philadelphia Friday, police said.

A single gunman came up to a group of people outside 2239 South Hobson Street at 9:24 p.m. and fired 11 rounds, said Lt. John Walker of Southwest Detectives.

A 25-year-old man was shot in the torso and was taken to the Hospital of the University of Pennsylvania in critical condition, Walker said. A 34-year-old man was shot in the arm and also was taken to the same hospital.

A 39-year-old woman and her 16-year-old son were both shot in the leg and were transported to Hahnemann University Hospital in stable condition.

The people on the street were watching activities related to a high school prom when the gunman emerged from an alleyway in a blue-hooded sweatshirt and white mask and opened fire, Walker said. He fled on foot.