A fire that officials are calling suspicious swept through a Northwest Washington rooming house yesterday morning, leaving homeless the 15 El Salvadoran immigrants who were living there. There were no injuries.

Police said there appeared to have been two separate fires in the three-story brick building at 1762 Corcoran St. NW. One fire started in a rear bedroom on the first floor, police said, and a second began in a bathroom on the third floor. Eventually the fires spread to all three floors in the house, police said.

Fire officials said the cause of the blaze, which caused $45,000 in damage to the eight-room row house is still under investigation.

A group of El Salvadoran men living in the house said they had been paying $100 to $160 a month each in rent, with their utilities included, but had had no gas or hot water since October. There was no heat in the building last winter, they said, and occassionally the electricity was cut off.

"The building is unlivable now, and it was before the fire, too," said D.C. Police Officer Albino Villaneuva, who was called on the scene to translate for the Hispanic tenants.

The tenants said they have been living in the United States for periods ranging from three weeks to two years. Most said they are working as busboys or dishwashers at Gusti's Restaurant, the American Cafe and the cafeteria of the World Bank.

Several of the tenants said they were asleep when the fire broke out about 9 a.m. Ten persons were evacuated by ladder, most wearing only their undercloths until trousers could be thrown to them, fire officials said.

Many of the tenants, still shirtless and shoeless, spent yesterday afternoon milling about in front of the house. Most said they would be able to spend the night with friends. The Red Cross also offered shelter and clothing.

The row house is owned by the Washington Mortgage Investment Co. in Adelphi, and recently was leased to Shashi Chopra, an Alexandria businessman.

Chopra acknowledged yesterday that the building had no gas or hot water when he took it over about a month ago. He said he was working to get the utilities restored.

A Fire Department spokesman said that possible fire code violations in the building are under investigation.