While their parents slept nearby, two children tipped over a space heater in their home in the Chillum section of Northeast yesterday, starting a fire that killed their 6-month-old sister, authorities said.

The blaze, which started shortly after 11 a.m. when the bedcovers were ignited by the overturned heater, briefly trapped the three children in the second-floor bedroom on the 5400 block of Eighth Street NE.

Officials said the fire illustrates the dangers of leaving children unattended with space heaters.

A police investigator familiar with the case said the parents were asleep in an adjoining bedroom. Investigators said the woman managed to rescue her two older children, Devin, 4, and Christopher, 2.

The baby, however, was left in the crib inside the burning bedroom. Neighbors and fire officials said the children's father at one point climbed on top of a porch roof and broke a window with his hands in an attempt to save the baby.

The father, Sanford Lamar, 39, received severe cuts to his right arm and was quickly driven out by the fire, which consumed the bedroom. Neighbors said Lamar, bleeding profusely, stood outside with his two children and distraught wife until firefighters arrived, neighbors said.

The baby, Ashel Ray Tyler, was found in her crib, suffering from first-, second- and third-degree burns over most of her body. She was taken to Children's Hospital, where she died shortly after 11:30 a.m., fire officials said. Neighbors and an investigator said the couple also have a girl, 10, who was in school when the fire broke out.

Yesterday afternoon, shocked neighbors gathered in front of the house, a well-kept brick structure with a neat garden. The mother, Robin Tyler, grew up on the block, in the house adjacent to the one damaged by the fire.

"That was a useless death," said Marietta Parker, a neighbor who has lived on the block for more than 30 years.

Tyler was taken to George Washington University Hospital, where a spokeswoman said she was suffering from smoke inhalation and second-degree burns on her right hand. She was listed in good condition. Lamar was taken to Washington Hospital Center, where a spokeswoman said he was in good condition after surgery.

The two children remained on the block long after their parents had been taken away by ambulance. They were placed in police cars and questioned separately by fire investigators trying to determine how the blaze started. They were then taken to a facility of the D.C. Department of Human Services.

The space heater was electric and conformed to fire department regulations, which ban kerosene heaters unless they are bolted to the floor and are properly ventilated.

Capt. Theodore Holmes, a department spokesman, said users of space heaters should read the manufacturer's instructions and make certain they are not placed near flammable materials. He said children should never be left alone in a room with a space heater.

"You have what is tantamount to an open flame. Anything it touches is liable to get ignited," Holmes said. "If you're going to have them in a room with a child, you ought to be in that room constantly."