The incident began shortly before 8 p.m. when a man flagged down Torrance officers and said his vehicle had been stolen.
The officers canvassed the area and found the vehicle in the parking lot of a Ralphs supermarket on Carson Street.
They say they encountered a man with a rifle in the vehicle. In the confrontation with the suspect, officers opened fire. He was struck and killed at the scene.
No officers were injured.
Investigators are continuing to look into the exact circumstances of the incident.