An argument on a basketball court outside a West Philadelphia recreation center turned deadly yesterday when two brothers were shot, one fatally, police said.

Shortly after 4 p.m. gunfire erupted outside the Shepard Recreation Center, 57th Street and Haverford Avenue, after an argument broke out during a pickup basketball game, said Homicide Sgt. Tim Cooney.

A 23-year-old man was shot once in the abdomen and taken to the Hospital of the University of Pennsylvania, where he was pronounced dead, Cooney said.

A stray bullet grazed the head of his 19-year-old brother, who was treated and released from HUP, Cooney said.

The victims were not identified and police reported no suspects.

Small puddles of water on the basketball court last night marked the spot where firefighters had washed away the blood of the 23-year-old.

Two cops stood next to a swing set, while a handful of youngsters quietly trudged out of the rec center after learning that football practice had been canceled.

Department of Recreation Commissioner Sue Slawson said that she closed the center after the shooting, displacing dozens of kids who were already there playing. "We can't just act like nothing happened here," she said.

Slawson noted that police officers routinely patrol Shepard, a sprawling, well-manicured site that includes tennis courts, two playgrounds and a pool.

"With all of the people who were out here, this person pulls out a gun, thinking he'll hit his target," she said, shaking her head. "Life is not worth losing over a basketball game. It's senseless."

Marvin Robinson, president of the Shepard Recreation Center Advisory Council, said he has long asked police and local politicians for more help to keep the center safe for kids.

He said that community members also need to step up. "It's not just on the cops," Robinson said. "We have to fight back. The kids have nowhere to go but here."

Police are still trying to determine the nature of the argument and who did the shooting.