An unidentified man was shot and killed and an off-duty D.C. homicide detective critically wounded last night in an exchange of shots that interrupted a wedding reception in a Northeast apartment house.

The deadly flurry of gunfire came about 11:30 p;m in the hallway of a building at 611 Edgewood St. NE, outside a room where the detective had been one of the guests at the receiption, authorities reported.

The detective was identified as Ron Washington. He was taken to Washington Hospital Center with gunshot wounds in his lower right abdomen and upper right thigh, and was undergoing surgery early this morning.

Authorities said two other persons may have been injured in the incident. One woman reportedly suffered a sprained ankle, and a man reportedly was struck on the head with a gun. Neither was said to be seriously injured.

According to neighbors and police inspector Melvin Winkelman, the reception attended by the detective was held in a social room on the first floor of the 11-story apartment house near Rhode Island Avenue NE.

Names of other guests or of the newly wed couple could not be learned immediately.

About 11:30 p.m., according to Winkelman, the detective was alerted to a disturbance under way outside the door of the party room. Washington was told that a man with a gun was involved.

Leaving the receiption, police said, Washington walked out into the apartment house hallway, where he saw a man pointing a gun at the building's security guard.

The detective ordered the man to drop the gun, Winkelman said, but the man turned towards Washington.

Within seconds, both men opened fire, according to the police account, although it was not immediately clear who shot first.

The gunman fired several shots, police said, and two struck the detective. Washington fired three times, hitting the gunman at least once in the upper body, and inflicting two other wounds, the police added.

Three ambulances were sent to the scene to take the victims to the hospital center. The unidentified gunman was pronounced dead there at 12:34 a.m. today.

Top police officials were notified of the incident and early today witnesses were still being interviewed. Some reported that the incident was precipitated when the gunman began arguing with the groom at the reception.