By Alecia Reid

PHILADELPHIA (CBS) — Four men were shot at a gas station in Southwest Philadelphia’s Elmwood neighborhood on Wednesday night. One of the victims is an employee who is now in critical condition.

Police say more than a dozen shots were fired from a semiautomatic weapon in front of the garage at 69th Street and Buist Avenue, around 7 p.m. Wednesday.

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Southwest detectives are carefully processing the scene to search for clues in the quadruple shooting.

“We found 15 spent shell casings. Most of those shell casings were just feet from a garage bay door attached to the gas station,” Philadelphia Police Chief Inspector Scott Small said.

Witnesses say an employee at the garage was working Wednesday night when an argument took place. The argument escalated and it led to the shooting.

“He’s shot multiple times in his chest, back and torso. He’s in critical condition, undergoing surgery at this time,” Small said.

“I’m so sad,” property owner Lal Singh said. “Thank God he’s alive.”

Twelfth District police initially found two victims in the parking lot of the garage and gas station. They were transported to Presbyterian Hospital.

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Two additional victims later showed up to the hospital by private vehicle.

It’s not clear how the three other victims were connected to the shooting, but they were shot in the shoulder or leg.

“I’ve been the owner here 21 years. We don’t have any problem like that,” Singh said.

Three parked vehicles were struck by gunfire. A part of the altercation may have also taken place a half-block away, where three shell casings were found on Theodore Street, behind the gas station.

“It appears that there was some sort of shootout at the garage door base and possibly someone was either chased or someone fired shots behind the garage,” Small said.

Police are now pouring through video surveillance cameras inside and outside the garage. As detectives continue to put the pieces together, they are at the hospital interviewing the victims.

No arrests have been made.

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For a list of gun violence resources in Philadelphia, click here.