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SAN DIEGO -- A man was fatally shot at close range by a semi-automatic assault rifle Saturday evening outside a fast-food restaurant, authorities confirmed.

The shooting happened at around 5:30 p.m. PT (8:30 a.m. ET) in the parking lot of a Carls' Jr. on Sweetwater Road in National City, Calif. The gunman fled the scene after fatally injuring a male victim.

The victim was shot approximately 10 times from a distance of about 10 to 15 feet, according to Lt. Robert Rounds. When police arrived, the victim was lying on the ground in critical condition.

He was transported to UCSD Medical Center, but died a short time later.

Police immediately began searching the area for the suspect, who fled the parking lot in a white 1970s Ford pickup truck with an orange stripe on it.

Investigators roped off the parking lot in the Sweetwater Town and Country Shopping Center with crime scene tape as they searched the area for bullet casings.

'Boom-boom-boom-boom'

Witnesses Muhammed Camran and Michael Ybarra told NBC 7 San Diego that they were right across the street at the time of the shooting, playing golf at a nearby golf course.

The sudden sounds of gunfire shocked both of them.

“We were over here at the golf course just hitting some balls and we hear a loud ‘boom.’ The first one was really distinctive like ‘boom-boom-boom-boom’ and we kind of ducked because it was out of nowhere,” recalled Camran.

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Meanwhile, witness Trevor Hermann was working at Pet Mart, less than 200 yards from the scene of the deadly shooting.

“I was helping a customer, looking at dog food, and then all of a sudden we heard all of the gunshot. Then I went out and thought it could have been someone's backfire from a truck, but I didn’t think that much, and then I looked further away and there was a guy just lying there,” he explained.

Hermann said he saw the suspect speeding away in an orange and white truck that drove right past his storefront.

“It had a little bit of speed on it and it went away a little quick, and that’s how I knew it was that truck that did the shooting,” he added.

Police say witnesses describe the suspect as a Hispanic male wearing a black-hooded sweatshirt. He was last seen driving east on Sweetwater Road in the distinctive truck.

The shooting victim's name has not yet been released. A report from the county Medical Examiner's office confirms the man was a 43-year-old National City resident.