All three victims were in their late teens or early 20s, East Whiteland Township Police Chief Frederick Rosato said. Their identities were being withheld until their families could be notified.
The shooting began shortly after 9:30 Monday night when employees of a KFC/Taco Bell at the Great Valley Center in Chester County began closing the restaurant for the night, Rosato said.
Five male workers went outside to empty the trash and, for an unknown reason, walked into the woods about 100 yards behind the restaurant, Rosato said.
Police believe one of the men pulled out a semiautomatic pistol and began shooting at the others, killing two, hitting another in the buttocks and missing the fourth, Rosato said. He said the gunman then stole the restaurant manager's vehicle and fled.
"We're still trying to filter out the motive," Rosato said.
Police had a description of the man and officers had stopped him near the shopping center at one point, but the man escaped on foot and was able to flee in another car, a police spokesman said.
Rosato said one of the victims died behind the restaurant Monday night. A second victim died at Paoli Memorial Hospital, hospital supervisor Doug Hughes said.
The third victim was expected to survive, Rosato said. A nursing supervisor at Brandywine Hospital, where officials said the man was taken, would not release any information.
Malvern is about 19 miles west of Philadelphia.
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