Nathaniel Haas realized the party he had thrown was getting out of hand when one of the guests tried to push a refrigerator down the basement stairs. When he saw people jumping through the living room ceiling from the attic rafters and hurling beer kegs against the walls to see who could make the biggest hole, Haas knew things were really out of control.

The party last June in Fredericksburg gave new meaning to the term "beer bash," and may go down in the annals of college revelry as one of the most expensive ever staged.

Haas, 22, of Marietta, Ohio, and his two housemates--Jeremiah Sutton, 20, of Timberville, Va., and Robert Henneberg, 21, of Falls Church--had to pay $21,000 in restitution last month to the National Park Service, which owns the 60-year-old brick house where the three Mary Washington College students were living.

"It became like an 'Animal House'-style party," Haas said, referring to the 1978 John Belushi movie. "It was definitely a costly beer party."

The Park Service bought the building early last year with the intention of expanding the adjacent Civil War battlefield park, letting the students stay in the house until their lease ran out June 30. The agency planned to either demolish the house or move it intact to another location.

After the students moved out their belongings and invited a few friends over for a final party, word spread quickly across the campus and through the town that a major bash was under way.

"Most people thought the house was going to be torn down," Haas said. "More and more people started showing up. It was ridiculous. There were people from bars downtown saying, 'I heard there was a house-trashing party.' "

Between 80 and 100 people crammed into the two-bedroom house, Haas said. Sometime after midnight, the three housemates fled, leaving the remaining partygoers to their own devices.

Later, park rangers were stunned by the extent of the damage. In November, they hauled the former housemates--now juniors--out of class, and federal prosecutors made them pay restitution. But that is not the end of it. An assistant U.S. attorney in Alexandria is pursuing at least 15 partygoers who allegedly caused damage.

They apparently weren't too hard to track down. A number of participants left graffiti on the walls, some of them signing their work. Among the writings was a "party roster" with more than 20 names.

As for the house, the Park Service plans to tear it down after all, Haas said.