Garrison, 26, was inside his sport utility vehicle when it crashed into a tree in Beverly Hills at about 11:50 p.m. local time, Sergeant Shan Davis said, adding that police were still investigating which of the car's four occupants was driving and what caused the collision.
Garrison received minor injuries, but a 17-year-old boy was pronounced dead at Cedars Sinai Medical Center following the accident. Two 15-year-old girls were also injured, one critically.
Garrison plays "Tweener" on the Fox jailhouse drama "Prison Break." Fox is a unit of News Corp.