The boy, whose age was not immediately known, was riding in a car in the area of Los Robles Avenue and Penn Street about 3 p.m. when he was shot, NBC4 reported.
The boy was taken to a hospital in critical condition, according to the Pasadena Police Department. No other injuries were reported.
A second shooting was reported in the area of Los Robles Avenue and Jackson Street soon after the boy was shot, though it was not immediately known if anyone was injured, according to police. Detectives were working to determine if the two shootings were related.
No suspect description was provided.