The California Polytechnic State University has banned fraternities and sororities from partying on campus due to sexual assault allegations. So instead, the students party off-campus and seriously injure themselves.

St. Patrick’s Day is still 10 days away, which is why local police were taken totally by surprise.

In a neighborhood near the university, a massive party to celebrate the Irish patron quickly spiraled out of control. Thousands of students, mostly dressed in green, attended the bash. It started Friday night and was still going strong as the sun began to rise Saturday morning.

Nearly 40 students were on the garage roof, presumably to watch the sunrise, when it collapsed beneath them. Screams were heard throughout the party. Nine students were were sent to the hospital.

While none of the injuries are life threatening. One student had his leg impaled by falling debris. Another suffered from a concussion. Several had neck and back grievances.

“This is completely unprecedented,” said Police Captain Chris Staley in an interview with the San Luis Obispo Tribune . “We’ve never had anything like this.”

Some students said the party took place two weeks early this year so as to not interfere with exams. Others said it was because the city fines double on popular partying days such as Halloween, St. Patrick’s Day, and Mardi Gras.

City and university police are conducting an investigation. This could lead to disciplinary measures for the party’s hosts.