SAN FRANCISCO -- Three members of a Yale University singing group allegedly beaten up after a New Year's Eve party last year have testified at the preliminary hearing in the case, one describing the attack as "pandemonium."

Richard Aicardi and Brian Dwyer, both 20, have been charged with felony counts of assault and of battery for an alleged attack on two members of the a cappella group the Baker's Dozen, Evan Gogel and William Bailey.

The incident took place at a Richmond District house party in the early morning hours of Jan. 1, 2007, reportedly after the group sang the national anthem at midnight, a Baker's Dozen tradition accompanied by a ceremonial drink.

Following that, a heated argument broke out between locals who attended the party and some members of the Baker's Dozen, group members Gogel, Bailey and Bryan Bibler testified Monday.]

All three said they, along with others in the group, were trying to leave the party to avoid further confrontation, when they were attacked outside on the street. Some reported being punched and kicked repeatedly while laying on the ground.

Though other members of the singing group were also reportedly attacked and injured, including one who suffered a broken jaw, prosecutors did not have enough evidence to file charges in those cases.

Bibler Monday described the situation outside on the street as "pandemonium."

"Basically, I saw BDs (Baker's Dozen members) getting hit and thrown to the ground, all over the place," Bibler said.

All three men identified Aicardi as having been involved in the dispute, Bailey testifying that Aicardi punched him once in the face.

Dwyer has not yet been identified in court by prosecution witnesses, though the preliminary hearing continues Tuesday.

The three men acknowledged that some of the members of the Baker's Dozen had been drinking earlier that day as they rode by van to San Francisco from a performance at a Lake Tahoe ski resort.

Gogel also admitted that there had been "trash talking, threats and taunting by both sides" during the party.

All three claimed that the members of the group left the party in order to avoid further confrontation.

The party took place inside the home of a San Francisco police sergeant and her husband, a retired San Francisco police sergeant, and had been organized by the couple's daughter, who invited the singing group.

The preliminary hearing, after which a judge will determine if there is enough evidence for a trial, is scheduled to continue Tuesday morning at 10:30 a.m.