So many homeless people have discovered Washington's newest shelter, a converted Metro bus parked at night beside the Farragut West subway station, that workers said yesterday they may be forced to send people elsewhere for lack of space.

As a cold rain fell Monday night, 44 people climbed aboard the makeshift shelter and a backup bus furnished temporarily by the District government, nearly filling them to capacity.

Last night, in milder, dryer weather, 25 persons had gathered at the buses by 10:30 p.m., and the backup bus again accommodated the overflow.

"Word's got out that we've got shelter, and people are coming from the parks and nearby areas," said Sloan Carlson, who helps staff the shelter. "I don't know if it would be possible to fit a couple others in."

The bus was arranged by local business leaders and officials under an agreement last week that ended a 33-day fast by Mitch Snyder and seven other advocates for the homeless. They had been protesting Metro's installation of gates to keep people out of Farragut West's escalator well at night.

In an interview Friday, Metro Board Chairman Joseph Alexander, a Fairfax supervisor, said the transit authority plans to build barriers at other Metro stations throughout the system.

A group of local business leaders paid about $8,500 to take the Farragut West bus out of the transit authority's reserve fleet and equip it with a toilet, fire extinguishers, window shades and baseboard heating. Half of its seats were removed, creating room for 20 to 24 people.

The District bus, which resembles a school bus, was stationed at the corner of 17th and I streets NW Friday as a stopgap measure until the Metro bus could be refitted. It remained in place after the blue mobile shelter arrived Monday night.

"Whether or not we'll retain two buses on an ongoing basis is a decision that has not yet been made. It is not the plan to do that," D.C. Social Services Commissioner Marjorie Hall Ellis said yesterday.

Within a week, two mobile trailers with a total of 36 beds for the homeless are expected to begin service in the city, Ellis said.

Fewer than 10 people regularly sought refuge in Farragut West's entrance area before the gates went up in mid-October, according to groups that minister to the homeless, but street people have come from throughout downtown to pass the night in the buses. Their numbers swelled from nine Friday to 17 Saturday and 25 Sunday.

Monday night, they nodded off to sleep as the windows fogged and the engines idled to keep the heat flowing.

"This is remarkable. This is damn good," one man exclaimed as he inspected the modified Metro bus.

"This is better than a shelter. You don't have to worry about being jumped" here, said another, Josh Burko, 38, who said he lost his front teeth and his wallet to an assailant in a D.C. shelter. Like others aboard the bus, Burko was turned away from full shelters and slept on the street before the buses were put in place.

The bus is staffed through the night by a security guard, a bus driver, and staff members from Christ House, a charitable group.

At least one man said he was disappointed with the result of weeks of protest at Farragut West, however. "The seats are just too narrow. I can't sleep sitting up," said Mark Parker, who stretched out in Farragut park Sunday night but boarded the Metro bus during the rain.

A yellow handwritten sign posted in the door of the blue Metro bus informed occupants of several rules, among them, no smoking, no drinking and no noise after 10 p.m.

Participants in negotiations over Farragut West said many issues, from legal liability to compliance with fire codes, had to be resolved.