A 15-year-old passenger in a car was killed and his companion wounded by at least one gunman who opened fire near a popular nightclub in Southeast Washington early yesterday, police said.

The shooting, one of three homicides in the District between Friday evening and early yesterday, stemmed from a dispute between Salvadorans and may be tied to recent violence in Alexandria, according to police sources.

The victim, Edwin Merino, was riding with a 19-year-old companion when another car containing at least four men pulled up alongside the vehicle at the intersection of First and M streets SE, in front of the nightclub Tracks.

"It was like a running thing," a detective said. "They were following the . . . car."

Police said several shots were fired, one fatally wounding Merino and another striking his companion in the leg. The name of the companion, who was treated at a District hospital and released, was withheld because he is a witness.

An officer on patrol spotted the assailants' car shortly after the shooting and followed it onto Interstate 295 south. The four suspects abandoned the car near Bolling Air Force Base. One was caught after a chase, but the others eluded the officers, police said.

The District's Rapid Deployment Unit, an anti-crime force working in Southeast, began searching the area. About three hours later, after receiving a report of two men trying to break into a car, officers from the unit found one of the suspects hiding in a Dumpster on the unit block of Danbury Street SW, a police source said.

The two suspects taken into custody were identified as Jose Agustin Guevara, 18, and Fermin Rivera, 19, both of Alexandria. Each was charged with first-degree murder while armed. Two other men, last seen on Chesapeake Street SE, are still being sought.

Last week, Alexandria police said two incidents this year involving Salvadorans -- a fatal shooting in January and a stabbing earlier this month -- occurred after the victims visited Washington nightclubs.

A District police source said Tracks, a club popular with Salvadorans, may have been the scene of a dispute earlier this year that marked the beginning of the violence. Merino, who lived on the 1400 block of Spring Road NW, apparently was going to the club when the shooting took place, but it is unclear whether the assailants were inside the club earlier in the evening, the source said.

Police yesterday also released the name of a grocer who was killed during a robbery attempt outside his store on First and U streets NW. The victim, Song Sun Sop, 50, of Silver Spring, was shot in the head about 10:15 p.m., when he was preparing to close his store. Police said there are no suspects in the case.

Like other grocers who work late nights, often alone and in unsafe areas, the victim in Friday night's fatal shooting was taking a chance, several merchants said yesterday.

Just a block from where Song was killed, another grocer said he has been held up twice at gunpoint. In each case, Kim Yung, 41, said, he has surprised the would-be robber with a gun.

The first time, last winter about 7 p.m., Kim said he got his gun from under the counter and pointed it at the armed man.

" 'Right now,' I told him. 'You kill me and I kill you,' " said Kim, who served in the Vietnam War. "He don't shoot. He miss his chance, but I shoot three times."

Kim said he did not report the first incident to police because his gun was not registered. There are several bullet holes on the door and the counter of his store, evidence of two exchanges with would-be robbers, Kim said.

After the second incident, Kim called police, he said, because he feared he had struck one of three men who tried to rob him at gunpoint. His gun was taken away by police, but Kim said he has replaced it with a registered rifle he bought for about $400.

Across the street from Song's store, in another market owned by Koreans, the owners also said they had been robbed. But unlike Kim, the owners there say they do not fight back.

"My dad doesn't believe in carrying guns. He doesn't want no gunfight," Nick Chang said. "If someone came in here with a gun, he'll just give up the money. Better than getting shot."

The third homicide victim, an unidentified man, was found on 51st and H streets SE with gunshot wounds. He was pronounced dead at 2 a.m. yesterday by the Medical Examiner's Office.

The three killings raised the District's record-setting homicide total to 480.