A Glenn Echo residence mysteriously blew up early yesterday morning in an explosion that fire officials say was the result of arson.

The two-story Cape Cod home at 6419 Ridge Dr., belonged to Geraldine Shuff, a secretary for the Secret Service. Shuff has been a patient at Doctor's Hospital since last Friday, according to fire officials, who said she was admitted after suffering a heart attack.

Neighbors said they were awakened around 2 a.m. by a loud blast and a "whooshing noise." Some neighbors reported hearing more than one explosion, according to fire officials.

When fire officials arrived on the scene at 2:17 a.m., the whole house was engulfed in flames and the second story soon caved in, fire officials reported. Parts of the house fell on top of a car which was parked in front of the residence.

The fire not fully under control until 11 a.m., officials said. Ann Malecki, who lives next door, said the explosion broke storm windows on three floors of her house and the heat was so intense that it scorched some woodwork.

Fire officials said the fire apparently was started inside the house, possibly the result of a flammable liquid that had been ignited.

Fire officials said Shuff was well liked in the neighborhood and had no known enemies. Police have no suspects in the fire, which caused $75,000 damage to the house and $25,000 to the contents.

Agents from the Bureau of Alcohol Tobacco and Firearms were called in to investigate the blaze when fire officials began suspecting that the house had exploded as a result of a bomb. But that theory was later discounted. It was originally thought that the house exploded because of malfunction in the gas system but later fire officials learned that the house is heated by an oil furnish.