Fifty-four residents were kept from their homes for a second day yesterday as city officials tried to determine the extent of contamination from a leaking underground gasoline tank in Southeast Washington.

Among the questions a number of city agencies were trying to answer was the extent of the damage and how a two-year-old gasoline tank at the 7th District police station ruptured, leaking between 2,000 and 3,000 gallons of gasoline.

The underground fiberglass tank, which holds 10,000 gallons of gasoline, was installed in 1988, when the station house at 2501 Alabama Ave. was constructed.

Most of the evacuated residents spent Wednesday night with friends and relatives, and they were expected to do so again last night. The Red Cross placed 17 people in a hotel in Northeast Washington, but only 13 were there yesterday, officials said. Five buildings were affected, all in the 3000 block of 30th Street SE. Police did not allow visitors on the block.

Fire officials spent the day ventilating apartments and the nearby sewers with fans, trying to reduce gasoline vapors. The point at which the gasoline entered the soil is still not determined, and the cleanup cannot begin until that's done, officials said.

The inspection yesterday revealed that the gasoline has seeped into the soil and the sewer lines, 10 to 12 feet below ground.

It is still not clear how extensive the contamination is, where the gasoline is going, or how long it will take to clean it up, said Janet McCormick, a spokeswoman for the city Department of Consumer and Regulatory Affairs.

At the scene yesterday, a fire hose pumped water into the sewer to dilute the gasoline. The gas pumps for the station are in the rear, and the tank itself is within 25 feet, fire officials said. Operations at the 7th Police District building were not affected either Wednesday or yesterday.

A company that specializes in cleaning up spills will conduct soil tests over the next few days and, at some point, the tank will be dug up and examined, officials said.

A scientist for the federal Environmental Protection Agency, Michael Cramer, said a two-year-old tank should not fail if it was properly constructed and installed.