VIDEO: Man dies after being punched at Lancaster Jack in the Box

LANCASTER, Calif. (KABC) -- A man in his 60s is dead after being punched at a Jack in the Box restaurant in Lancaster on Thursday.

Los Angeles County sheriff's detectives responded to a call of an assault at the restaurant's parking lot in the 43600 block of 10th Street West at approximately 12:45 p.m.

The victim, whose name was not released, was punched once by a young man in his 20s. The victim sustained "obvious trauma" and was pronounced dead at a nearby hospital, sheriff's officials said.

Surveillance video of the assault was later released. The victim is seen driving out of the fast-food chain and saying something to people inside a champagne-colored sedan. Arguing, the suspect gets out of the sedan, and the victim also steps out of his truck.

Not long after, the suspect throws one hard blow, and the victim goes down.

Sheriff's officials said the suspect is believed to have fled in the champagne-colored, four-door sedan, which was last seen northbound on 10th Avenue West.

The motive behind the attack was not immediately known. It's also not clear whether the two knew each other.

Anyone with more information is encouraged to contact the Los Angeles County Sheriff's Department's Homicide Bureau at (323) 890-5500.