The shooting happened at about 10 a.m. when a gunman walked up to an open garage at 83 Arleta Ave. and opened fire, hitting three males and a female, police Capt. Louis Cassanego said.
Afterward, the shooter, described as a black male in his late teens, ran to a waiting brownish sport utility vehicle or minivan driven by a second person and fled, Cassanego said.
The victims were taken to a hospital where one was said to be in critical condition. The other three were listed as stable, police Officer Albie Esparza said.
Esparza said it appears the shooting was gang-related. No arrests have been made in the case.
Shortly before 11:30 a.m., Mayor Gavin Newsom arrived at the crime scene. The area around the tan, two-story home on Arleta Avenue remained blocked off for the police investigation.
Cassanego described the neighborhood as "blue-collar" and said it is "usually pretty quiet."
Police belive the shooting may be gang-related.
ABC7 News contributed to this report