John Oliver stayed at home a few minutes longer than usual Wednesday evening to watch the television program "Diff'rent Strokes" with his wife and two children before he left for downtown Washington and the part-time job he works nights.

When he returned about 11 p.m. from shampooing office carpets, he wasn't able to get his wife to answer his knocks at 160 Darrington St. SW and, sensing something was wrong, broke down the door to gain entry.

Inside, amid air that burned his nostrils, Oliver found his wife and children unconscious in an upstairs bedroom, the television still on. Ruby Oliver, 48, and Margaret Oliver, 4, were pronounced dead of carbon monoxide poisoning a short time later at Greater Southeast Community Hospital. John I. Oliver, 8, was in critical but stable condition last night at Children's Hospital.

Yesterday, D.C. police said the deadly carbon monoxide probably was produced by the 7-year-old furnace in the Olivers' two-story brick house.

Kattie Magill, a spokeswoman for the Washington Gas Co., said the utility had refused to restart the furnace when gas service, which had been cut off for nonpayment of a bill, was restored on Nov. 22.

A repairman who inspected appliances at the house when the gas was turned back on "found the furnace and water heater to be in such poor condition that they could not be used," said Magill. "He turned the stove on and left Mrs. Oliver a written notice that the furnace and heater needed repair."

Magill said pink tags, a widely recognized gas industry warning device, were attached to the furnace and water heater indicating that they were not to be restarted until they were repaired. Ruby Oliver also signed a utility company form saying she understood the appliances were unsafe and had to be repaired by a licensed contractor, Magill said.

John Oliver said yesterday that on the day the gas was restored, "I went to the basement and turned [the furnace] on. I was mad at her [his wife] for not insisting that the serviceman do it."

Oliver said that no tag had been placed on the furnace and that the gas company forms were given to his wife, who put them atop the refrigerator.

Oliver was unable during an interview to find the gas company notice as he rummaged through papers atop the refrigerator. "She told me that they said the furnace needed a filter," Oliver said.

Magill said that it was possible that the family had felt the ill effects of carbon monoxide for several days. She explained that the odorless, tasteless gas "will make you feel lethargic and sleepy and may give you a headache."

"If the family was asleep," Magill said, "it is possible that they weren't aware of the gas at all."

Oliver, whose main job is as a bricklayer for Atlantic Masonry, said that he had installed slide bolts on the front and back doors after a burglary attempt a month ago and that he insisted that his wife keep the house locked whenever he was away. When he arrived home at night from his second job, Oliver said, he would knock on the door and his wife would let him in.

On Wednesday night, Oliver said, "I knocked on the back door and didn't get an answer, so I came round front and knocked on that door. When my wife didn't come to the door, I knew something was wrong. I kicked in the door, busted it all up."

Oliver said he rushed up the stairs to the bedroom where his family watched TV.

"The TV was still running and I switched it off," said Oliver. "Then I tried to wake them up. They were all laying on the bed together. I shook them, but they wouldn't wake up. I picked up my little girl . . . ," Oliver said, his voice breaking as he turned away to wipe tears from his eyes.

"I carried them all down here by the door and then I called 911," Oliver said as he gestured toward the foot of the stairway where he placed his wife and children.

As he waited for an ambulance, Oliver said, he went to the basement and shut off the furnace. He found Killer, the family's Doberman pinscher, apparently unharmed in the basement.

Oliver's next-door neighbor, Grace Peterson, 53, said she heard Oliver yelling to his wife through the front door about 11 p.m. and then heard Oliver break in the door. A few minutes later, Peterson said, she heard Oliver yelling that his family was dying.

Peterson said that firefighters later checked her house and found fumes had seeped into her house but that her furnace was functioning properly.

Twelve hours after the tragedy at his house, Oliver packed a bag and said he was going to stay with relatives for a while.

"I've got to get my wife and daughter taken care of," said Oliver, who had no life insurance on his family.

"Then I will come back and fix the house back up. It burned down in 1977 and I rebuilt it the next year," Oliver said. "I'll just have to do it again. I've lived here 18 years and this is my home."