A shooting outside a busy transit hub in Philadelphia left a man in critical condition Sunday afternoon.

A man was at the Market-Frankford Line station at 60th and Market streets in West Philadelphia shortly after noon when someone opened fire on him, shooting him four times, according to initial police information.

Police took the victim, who was unidentified, to Presbyterian Hospital. He was in critical condition about 1 p.m. Sunday.

Investigators were working to determine what motivated the shooting and who was responsible later Sunday. No other injuries were reported.