An ambulance and a group of Harvard University Police officers descended on the sixth semiannual Leverett House 80s Dance on Saturday night to stop what some students feared were the beginnings of a riot.

While more than 750 students danced to the songs of Wham! and the Bangles in the Leverett dining hall, hundreds more tried to push their way in, forcing the Harvard University Police Department (HUPD) detail officer on hand to call for backup.

Students and officers had different perceptions of the HUPD response to the situation.

While students said six or seven officers brandishing nightsticks tried to break up the crowd in the Leverett court-yard, an HUPD official said four or five officers responded to a routine call for backup.

According to Leverett House Committee Chair Russel G. Perkins '97, the episode began at around 11:15 p.m., after the number of students in the dining hall exceeded safe limits. Door attendants stopped the flow of students into the dining hall, permitting only one person in for each person who left.

"Once the line stopped flowing in, it started to back up," Perkins said. "They started to get a little rowdy and people started to push. People were getting squished. People slipped into their mob mentality."

When house tutors told the D.J. to stop the music for the purpose of crowd control, partygoers continued to sing "Celebration" by Kool and the Gang.

At 11:47, the HUPD watch officer on duty felt the crowd outside was getting too large and called for backup, accord- ing to Sgt. Robert J. Kotowski.

Police dismissed the episode as a routine action, but students on the scene said the officers took the incident seriously.

"They kind of came in thinking it was a riot, with their clubs up," Perkins said. "But no force was used at all."

Students said they were afraid those pushing in line and moshing might create a dangerous situation.

"I was just on line and there were about a couple hundred people behind me and one guy was thrown on top of the people and was carried over the crowd horizontally," said Alexis Z. Martin '98.

"I was right at the front of the line getting pushed up against chair," Martin said. "There were some big guys pushing. I jumped up on top of the chair so I wouldn't get hurt."

She said the detail officer commanded students to back off and get away from him.

"The cops were screaming. I saw one cop pull away a guy that was harassing the first cop," Martin said.

Leverett House Master John E. Dowling said he tried to make his way to the entrance but could not get to the door because of the crowd congestion.