A 17-year-old boy was critically wounded in a shooting Tuesday afternoon in the South Side Back of the Yards neighborhood.

The teenager was walking in the 1800 block of West 45th Street about 1:45 p.m. when someone approached from behind and shot him multiple times in the back, according to Chicago Police.

He was taken in critical condition to Stroger Hospital, police said.

A police source said the shooting was thought to be gang-related.