AMHERST, Mass. - A pre-St. Patrick's Day celebration near the flagship campus of the University of Massachusetts on Saturday spiraled out of control, pitting police in riot gear against thousands of drunken and unruly revelers at the annual "Blarney Blowout." There were more than 70 arrests and four officers were injured in the clashes that included some students throwing beer bottles, cans and snowballs, officials said.