Philadelphia police are still searching for the men accused of beating up a Woodbridge police officer who attended the National Hockey League's Winter Classic event, held Monday in Philadelphia.

After the event, Woodbridge police officer Neal Auricchio and a friend were near Geno's Steaks wearing New York Rangers jerseys. A video that was posted on YouTube shows the attack.

Investigators say a man in a Flyers jersey is the main aggressor, throwing the first punch after a verbal dispute. Authorities say two other men also joined in the fight. Philadelphia police released an edited version of the YouTube video, which ends with one of the victims lying stunned on the street.

Auricchio's father, Neal Auricchio Sr., tells News 12 New Jersey his son, a former Marine and Iraq war veteran, may have also suffered a concussion. His father says they will know more Monday when they get the results of a CAT scan. The second victim has not been identified.

Sports psychologists say attacks like this have to do with stress and the need to be part of a group. Some see rival fans as a threat to that group dynamic. In most instances of fan violence, alcohol is involved. The director of the Woodbridge Police Department says it isn't an excuse.