A 12-year-old girl was seriously wounded last night when she was hit by a stray bullet during an outburst of gunfire in Northwest Washington, D.C. police reported.

The girl was struck in the abdomen while on the porch of a house in the Petworth area when shots were fired on the street shortly before 9 p.m., police said.

The name of the wounded girl was not immediately available. Police said she was undergoing surgery early today and was in stable condition.

About 12 shots apparently were fired from two guns at Shepherd Street and Illinois Avenue. Police said the shooting may have involved a red motorcycle and two cars and may have stemmed from an area rivalry. As of early this morning, no arrests had been reported.

D.C. Police Chief Charles H. Ramsey, who went to the scene, vigorously denounced the violence. "They don't care who they hit," Ramsey said. "It just baffles me that people are so reckless."

The shooting occurred less than three weeks after 8-year-old Chelsea Cromartie was killed by a stray bullet while she was watching television at her aunt's house in Northeast Washington.

When Chelsea was killed May 3, she became the 13th person age 17 or younger to be slain in the District this year. Authorities said that was more child homicides than in all of last year.

Two brothers, ages 21 and 23, have been arrested and charged in connection with Chelsea's death.

In last night's incident, Lt. Teresa Brown said investigators were trying to determine whether occupants of the two cars were firing at each other and whether one of the two people on the motorcycle may have fired at one of the cars.

The shooting occurred in what residents described as a middle-class neighborhood of mostly owner-occupied rowhouses. It is a couple of blocks northwest of the U.S. Armed Forces Retirement Home, formerly known as the Soldiers and Airmen's Home.

One Illinois Avenue resident said she was watching "The Sopranos" on television -- a show about members of organized crime -- when she heard the gunshots outside.

She said that at that time she heard a sound like a bullet striking brick or stone, which made her momentarily fearful to look outside.

When she did, she said, the street, which had earlier been filled with the sounds of children playing, had fallen suddenly silent. Another neighbor reported hearing the shrieks of children after the shots were fired.

After being hit while on the porch of a house, the girl apparently was quickly taken inside. A few minutes later, a neighbor said, she saw the girl being carried out of the house to an ambulance.

Police recovered about a dozen shell casings at the scene of the shooting. One police official said the casings came from bullets of at least two calibers, supporting the idea that more than one gun was involved.

One 40-year resident of the area said he had been hearing shots in the vicinity since 4 a.m.

"I'm just sick of this," said the man, who said he was too apprehensive to give his name. "This doesn't make any sense."

D.C. Council member Adrian M. Fenty (D-Ward 4), who represents the area where the shooting occurred, said a stretch of Shepherd Street between Fourth Street and Georgia Avenue had been designated a "hot spot" meriting special police attention. Fourteen District neighborhoods have been designated as hot spots.

Fenty voiced frustration at the scene that the designation had not been enough to curb violence. "We're going to have to find a way to tell the police that they're not doing the job in the neighborhood," he said.

Police said they were trying to determine whether a shooting, possibly a drive-by attack, about 4:30 p.m. yesterday on Quincy Street NW might have been related to last night's violence.

Some neighbors interviewed last night said their block was relatively quiet most of the time, although illicit activity occurs not far away. One of them said it was a diverse, multiethnic neighborhood made up of people from all walks of life.

On Jan. 19, Martin Luther King Day, three youths were shot in a car in the 400 block of Shepherd Street, a few yards from where yesterday's shooting occurred. The driver of the vehicle was killed; two other youths were seriously wounded.

Police gather near evidence markers in the Petworth area. The shooting was less than three weeks after Chelsea Cromartie, 8, died from a stray bullet.