An unidentified man was shot and killed on a Southeast Washington street last night only yards from where another was shot and seriously wounded in an earlier and apparently unrelated incident, authorities reported.

The 11:30 p.m. killing in the 3100 block of 15th Place SE was the city's second homicide of the day. About 5 p.m., police found the body of an unidentified 18-year-old man in the hallway of a building in the 200 block of 51st Street NE. The man had been shot several times.

In addition, police said at least four other people were shot last night, three in a single incident in the 200 block of 46th Street NE. None of their wounds was believed to be life-threatening, and no other details were known.

In another incident, a man sitting on his porch in the 1400 block of D Street NE was grazed in the head by a bullet, police said. He was treated at the scene.

The fatal shooting on 15th Place was witnessed by several people, who said they saw the victim running across the street as shots were fired from what police said was an automatic or semiautomatic weapon.

The man fell in the yard of an apartment development on the block and was taken to D.C. General Hospital, where he died.

The incident occurred about 100 yards from the site of a 9:50 p.m. shooting in which a man was shot several times after what police described as a dispute.

The man, whose name was not released, was taken to Washington Hospital Center, where he underwent surgery early today.

Residents of the area said they weren't surprised by the outbreak of violence on their street, saying that they hear gunfire regularly at night.

One resident said that the block has been known as a major crack cocaine market, but that drug selling and drug-related violence had abated in recent months.