An early morning fire raged through the basement of a Mount Pleasant row house in Northwest Washington yesterday, killing nine persons, including seven itinerant Salvadoran laborers.

Seven residents, including four children, were injured while trying to escape the flames and heavy smoke at 1629 Irving St. that were apparently caused when clothing and debris stored near a water heater ignited about 3:18 a.m. Nearly all the occupants were asleep when the blaze broke out.

The blaze was the city's deadliest in six years. Ten mentally ill women who were outpatients from St. Elizabeths Hospital were killed in an April 1979 fire that occurred two blocks away on Lamont Street.

Mount Pleasant, a small, turn-of-the-century neighborhood between 16th Street and the National Zoo, has become a haven for newly arrived immigrants from Central America. The neighborhood has the city's largest concentration of Hispanic families. It is one of the most diverse in the District, with immigrants living side-by-side with blacks and young white couples.

The neighborhood has an abundance of large brick houses, with as many as 30 people living in some of them, according to city officials.

An estimated 90 firefighters and 40 pieces of equipment responded to the fire, which sent up flames and billowed heavy black smoke for an hour and a half.

It took seven minutes before hoses were used on the fire because so many fire victims had to be removed first, D.C. fire authorities said.

"It was hectic because all the bodies were coming out and they were performing CPR," said one fire official. "All of the people ran to the back door and got overcome. That's where all the bodies were helter-skelter."

At least 10 Salvadoran immigrants lived in the basement apartment, according to Jose Saravia, 39, one of the few men living in the apartment who escaped death. Each man paid $50 in monthly rent, he said.

"I was brewing coffee and I heard the heater rattling, and then it exploded," Saravia said yesterday, standing in front of the charred hulk and gesturing with heavily bandaged arms. "I ran to the front of the basement . The door was bolted. Two of my friends were behind me, pushing against the door."

The bolt was stiff because of the cold, but it finally gave, Saravia said. The flames spread so rapidly, he said, that those sleeping had no time to escape.

A spokesman for the Washington Gas Light Co. said the fire melted soldered gas line connections, allowing escaping gas to feed the fire.

The dead were tentatively identified by neighbors, relatives and District homicide detectives. They included Anastasio Chicas, brothers Vincente and Anselmo Cruz, Baltazar Salmeron, Manuel Ayala, Jorge Chirino and Jose Villatoro -- all believed to be recent Salvadoran immigrants working as construction laborers. The dead included Teresa Williams of Washington and Melissa Cole, most recently of Springfield.

At least two survivors were reported to be in serious condition at Washington Hospital Center. One man, who had second- and third-degree burns, could not be identified yesterday. The other is Mario Benavides, 41, who is suffering from smoke inhalation, according to the hospital.

Two children, David Alcantara, 5, and a 2-month-old boy who was not identified, were reported in good condition at Children's Hospital suffering from smoke inhalation. The condition of the other three injured could not be learned.

The three-story brick house, which was built in 1912 and valued at $93,897, is owned by Koula T. Harris, who lives in Bethesda. She said she lived in the house from 1954 through 1961. The family rents the home to Laurent and Mercedes Ross, who occupy the upper floors and sublet the basement and an upper room.

The six occupants of the upper floors raced to the locked first-floor front door.

Daniel delValle, who teaches English to immigrants in the Fairfax County schools and rents a room on the second floor, said he was awakened by Laurent Ross with news of the fire. DelValle said he dressed hurriedly and along with Laurent and Mercedes Ross and her two children, David and Erwin Alcantara, made their way through the smoke to the front door.

But the key to open the deadbolt lock was missing, he said.

"The smoke was like overcoming us," he said. They rushed back up the stairs, losing track of David, delValle said.

"I just remember jumping out the second-story window," he said. He landed on the roof of the porch and slid down a drain pipe. Mercedes Ross, who is eight months pregnant, climbed down from the porch roof on a ladder extended by neighbor Norma Egoavil, 42.

Laurent Ross tossed Erwin, 7, to neighbors standing on the roof of the next porch, delValle said. Ross then jumped to safety on the neighbors' porch.

Firefighters arrived within minutes and rescued David, delValle said.

Harris, the property owner, said the house had been in "excellent condition." Harris' son-in-law, Theodore Roumel, who handles the rental property with his wife Maria, said he was told that four adults had moved into the basement a month ago.

The two-alarm blaze apparently started in a utility closet containing a water heater and furnace that was in the front of the basement apartment.

Deputy Fire Chief Ray Alfred said the closet was filled with paper, clothes, aerosol cans and other combustible materials that may have been ignited by the heater's pilot light. A metal guard in front of the pilot light had been removed and was found next to the heater, according to Katie Magill, a spokeswoman for the gas company.

Neighbors said there had been a party in the basement earlier in the evening. Antonio Lazo, 23, a cousin of Jose Villatoro, who died in the blaze, said he left the party two hours before the fire began.

Police investigators blamed heavy drinking for the large death toll, saying it impaired some occupants' ability to escape.

Alice Burton, who lived nearby, said she visited the apartment Saturday to see her friend Teresa Williams. "She was such a nice person -- everyone knew her on this street."

Burton said another victim, Melissa Cole, had been living in Springfield with her husband and 2-year-old daughter until recently. "She just moved in four days ago," Burton said.

Several city officials said crowding is a serious safety hazard in the Mount Pleasant area.

"This may be the first of many tragedies like this," said Arlene Gillespie, director of city's Office of Latino Affairs. "We have overcrowding in all of the Adams Morgan-Mount Pleasant area."

D.C. City Council member Frank Smith (D-Ward 1), whose ward includes Mount Pleasant, said, "It's an awful thing to have happen. Every winter we go through these kinds of deaths because of fires."

He said he is supporting a project at the University of the District of Columbia to canvass the neighborhood and give residents advice on the need for smoke detectors and planned escape routes.

Deputy Fire Chief Alfred said there was a smoke detector on the second floor, but it was unclear whether one was located in the basement because its ceiling collapsed in the blaze.