A 12-year-old boy was shot in the head and critically wounded yesterday afternoon as he played at a friend's house in the 3100 block of Apple Road NE, District police said.

The boy, who was not identified, was shot apparently when a gun being held by his 12-year-old friend accidentally went off, homicide Lt. Tommy Musgrove said. The victim was taken to Children's Hospital, where he underwent surgery and was listed in critical condition last night.

Musgrove said the children were alone in the house when the shooting occurred.

"It's a tragic situation, one friend shooting another . . . a real tragedy," Musgrove said.

Earlier yesterday, two men were killed in the District during separate incidents.

A 19-year-old man who had been shot several times was found shortly after 1 a.m. in a drugstore parking lot in the 2600 block of Naylor Road SE, police said. The victim's name was withheld by authorities pending notification of relatives.

Police said another man was fatally stabbed shortly after 3:30 a.m. in the 2600 block of 13th Street NW.

The man, who was carrying no identification when police found him, was taken to Howard University Hospital and pronounced dead at 4:14 a.m.

The Apple Road incident marked at least the third time in the last year in which a District child was shot while playing with a weapon.

A 13-year-old Northeast Washington youth was shot in the groin by his older brother on Dec. 25 as they played in the basement of their home in the 6300 block of North Capitol Street.

Last May, Marlon Humphries, 13, was shot in the neck as he and a friend played with a gun in Humphries's apartment in the unit block of Darrington Street SW.