Gunmen Ambush Car at Gas Station in Horrifying Surveillance Footage

A group of gunmen got the drop on some unsuspecting people at a gas station ... firing off multiple shots before quickly booking it in newly released surveillance video.

Cops finally released footage from the shooting last year that left a man dead ... and, it begins with a white car pulling into a South L.A. parking lot.

Check out the clip ... two people jump out the back of the car, guns cocked and ready -- and they start shooting, one firing at a car parked next to a gas pump and the other firing at another car and a person sprinting away down the sidewalk.

The two people then jump back in the car and the vehicle bolts from the parking lot ... the whole incident took less than 10 seconds.

Police say 32-year-old Marquette Scott who was sitting in the car at the gas pump was shot and killed ... and, cops say they still don't know the motive for the shooting.

They offered a $50k reward to anyone with information on the shooting back in April after investigators exhausted all available leads.