A Northern Virginia couple died early yesterday in a fire that raced through their six-room house with heat so intense that it melted an aluminium porch door and buckled a refrigerator.

The bodies of Robert Lloyd Carey, 69, a retired Air Force officer, and his wife, Bobbie Frances Carey, 60, a real estate broker, were found shortly after 3:30 a.m. in the gutted remains of their $71,125, one-story white clapboard house at 930 Park St. SE in Vienna, Fairfax County fire authorities said.

Investigators said they did not know the cause of the fire, but said it appeared to have been accidental and could have started in the den. They said they believed the house had at least one smoke detector, but did not know if it was working.

Tricia Madden, 25, a neighbor who works for a construction company, said she ran out of her home about 3:15 a.m. and found flames leaping 20 feet into the air from the rear of the Carey house.

Arthur Clark, 42, another neighbor and a building manager for the Navy Department, said the sound of fire engines awakened him a few minutes later. "When I looked, the whole house was engulfed in flames," he said.

Firefighters said it took about 20 minutes to bring the blaze under control. Carey's body was found in the master bedroom, firefighters said. His wife, a former president of the Northern Virginia Board of Realtors, was discovered dead in a rear bathroom.

Autopsies are scheduled for today, according to the Northern Virginia medical examiner's office.

Mrs. Carey started her career in real estate in l959. She owned a company known as the Phoenix Group, which was purchased by Mount Vernon Realty Inc., for whom she continued to work.

"She was a very vivacious, vital lady," said Joseph Hayden, a spokesman for the Northern Virginia Board of Realtors. "Whatever the cause, you can be sure she would be in the middle of it, and encouraging others to get on board and participate . . . . "