Six partygoers attending a fundraising event at an Arlington fire station were arrested and charged with disorderly conduct late Friday after a melee broke out when police and state liquor officials raided the gathering.

Arlington police spokesman Walter Summers said "all hell broke loose" after one of those arrested, Joseph Donelly, 23, of 1618 N. Randolph St., allegedly struck police officer in the chest.

Some 150 people attending the party in a rented room of the Cherrydale fire station threw beer at police an state Alcoholic Beverage Control Commission officer, and police used Mace to defend themselves, Summers said.

Donelly's mother, Lorraine Crozier, charged yesterday police beat her son over the head with billy clubs until he was knocked unconscious.

"He's been beaten by the police many times," Crozier said. "This is one time they're not going to get away with it."

Donelly was taken to Arlington Hospital by police, but refused treatment for head wounds, Crozier said. Police said internal investigation of the incident would depend on whether a complaint of police brutaltiy is filed.

Also arrested were Donelly's brother, David, 22, of the same address, and four juveniles whose names were not released by authorities.

Summers said six police officers accompanied two ABC inspectors to the party to close it down because of a reported illegal sale of alcohol. The party, its organizers said, was given to raise money for an unidentified Arlington man facing trial.

Party organizers said they were asking a minimum $3 donation at the door. They said they had checked with the ABC inspectors last Tuesday and were told that asking for a donation at a function serving liquor would be legal.

Frank Reed, head of the ABC inspection division for Northern Virginia, said yesterday, however, that liquor served at a function where donations are requested constitutes a sale for which a permit is required.

Police said yesterday that ABC in spectors served two organizers with a summons shortly after arriving at the party. Police then turned on the lights, confiscated the beer, and told those assemled to leave.

Organizers for the party contend that the police caused the ensuing riot by showing up in full gear and "brutalizing" some party-goers.

Tracy Hobbs, one person at the party, said he saw five policemen gang up against Donelly. "They beat him repeatedly. They got all their kicks out against him," he said.

The six who were arrested face arraignment today.