The waving hand of Brenda J. Harris, 17, loosely formed the hand signal for a gang and led to her fatal shooting Friday by a rival gang here, police investigators say.

Tacoma police said Harris' fingers appeared like the letter P upside down - the gang hand signal for Piru Bloods, rivals of the Crips street gang.Police said Harris, a passenger in a four-wheel-drive vehicle, waved to a man standing in Tacoma's Eastside neighborhood and talking to several men - members of the Crips - in a parked car.

Police said the men in the car chased the four-wheel-drive vehicle several hundred yards to a dead-end street and fired between 13 and 20 rounds with at least three different firearms.

Investigators said one of the weapons may have been a rifle and one may have been a shotgun. They have not determined what the third weapon was.

One round burst through the rear window of the wheel-drive vehicle, striking Harris in the back of her head, police said.

The driver of the four-wheel-drive vehicle, Warren Smith, 22, an Army trooper from nearby Fort Lewis, told his two passengers to duck. Smith, uninjured, backed into an apartment complex driveway, jumped out and climbed over a fence.

He returned when he heard tires squealing away, police said. The other passenger, Tara Warfel, 17, of Tacoma, escaped injury.

Police arrested three men aged 26, 19 and 18, along with a juvenile, all of Tacoma, on suspicion of first-degree murder.

The juvenile was arrested within an hour of the shooting, police said, when he returned to the scene to look for a missing part to the automobile from which the shots were fired.