INDIANA, Pa. (AP) -- Large crowds and alcohol-related disturbances kept police in western Pennsylvania busy at a pre-St. Patrick's Day celebration around Indiana University of Pennsylvania over the weekend. Sgt. William Vojtek of the Indiana borough police department told the Pittsburgh Tribune-Review that it was the third year in a row for the unofficial party in streets surrounding the school. He said there were numerous arrests Saturday for public drunkenness, underage drinking and retail theft, and police were also investigating a report of a sexual assault. Police didn't have an exact number of arrests or charges Monday. Hundreds filled the streets as warm weather brought out winter-weary students and other young people after months of frigid temperatures. Students, who sported a variety of green attire or even spray-painted hair, said they were celebrating early because they will be on spring break next week on St. Patrick's Day. Following similar disruptions last year, university officials said they had tried to head off a recurrence through educational programs about alcohol abuse and alternative weekend activities. "We are doing as much as we change to change the expectations for what his event is," university spokeswoman Michelle Fryling said. "Unfortunately it is not unique to IUP." Fryling said officials don't know how many students are involved since "there are a tremendous number of visitors who come into the community for this event." School officials will work with police to try to identify any students involved, and anyone charged with a crime could face suspension or even expulsion, she said.