PHILADELPHIA —  A Kmart worker was shot and critically wounded at a store loading dock Tuesday morning after he intervened in an argument between a co-worker and her boyfriend, police said.

The 35-year-old victim was shot three times, in the head, arm and chest, around 9:30 a.m., according to police. He was in critical condition at a hospital.

The gunman began arguing with his girlfriend outside the store and then followed her inside, according to police Lt. Frank Vanore. He followed her through the store and back to the loading dock, where he pulled out a handgun and opened fire, striking the employee who intervened, according to police.

Officers fanned out around the northeast Philadelphia store in search of the alleged gunman, identified by police as Daryl Anthony Birch, 30. A telephone listing for Birch could not immediately be located by The Associated Press.

Police were turning away customers at the door of the store and investigators could be seen talking to people inside.

Kim Freely, a Chicago-based Kmart spokeswoman, declined to comment.

A high school and two elementary schools, one of them several blocks from the scene, were locked down after the shooting, said Fernando Gallardo, a spokesman for the city school district.

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