A pre-St. Patrick's Day celebration near the flagship campus of the University of Massachusetts spiraled out of control, pitting police against thousands of drunken and unruly revelers at the annual "Blarney Blowout."

Officials said early Sunday there were 73 arrests and four officers were injured in the clashes that included some students throwing beer bottles, cans and snowballs.

Amherst police said authorities spent most of the day Saturday attempting to disperse several large gatherings around the UMass campus for the party traditionally held the Saturday before spring break. The partying carried into early Sunday.

Amherst Police Capt. Jennifer Gundersen has called the partying "extremely disturbing and unsafe."

A UMass spokesman says students who were arrested will be reviewed under the school's code of conduct and could face sanctions.