Three children died in their Northeast Washington row house yesterday morning and a fourth was in critical condition last night after flames engulfed the home while their mother was out, D.C. fire officials and neighbors said.

The fourth child, an infant, was rescued from the blaze when his mother returned home and tossed him from a second-story window to a neighbor below, witnesses said.

The fire, according to officials, started in the first-floor living room of the family's rented row house at 1147 Third St. NE.

Firefighters went to the scene at 11:42 a.m., shortly after the fire broke out, and extinguished the blaze within 10 minutes.

The dead children were identified by officials as Marketa, 4, Charles, 3, and Mark Bradford, 2.

Two-month-old Michael was thrown by his mother, Tina Bradford, 23, to a neighbor and remains in critical condition at Children's Hospital in Washington, according to officials.

Officials yesterday were still investigating the cause of the blaze, which they said burned with remarkable speed as it spread upstairs toward the children.

"The house had a narrow, spiraling stairway," said Lt. Theodore Holmes, a spokesman for the D.C. Fire Department.

"The fire and smoke was channeled right up that stairway. The children probably didn't have much of a chance."

The children's mother, according to Ida J. Chase, a next-door neighbor and family friend, had left the home to make a phone call.

Chase said the house did not have a smoke detector.

Tina Bradford, according to Tracie Banks, another neighbor, managed to save Michael by climbing through a second-story window and throwing him down to a neighbor as flames poured out of other windows in the house. Banks said she caught the infant.

Bradford was unemployed and not married, according to Chase, who said the children's father, Charles Johnson, seldom lived at the home.

Michael Bradford was taken to Capitol Hill Hospital, then transferred to Children's Hospital, officials said.

His mother was treated at Capitol Hill Hospital and released.