MINNEAPOLIS -- University of Minnesota leaders are warning students they'll have no tolerance for bad behavior Saturday night after the Gopher men's hockey game against Union College.

After the Gophers won the semifinal Frozen Four game against North Dakota on Thursday, fans converged on Dinkytown.

They got rowdy, throwing bottles, jumping onto a police car and damaging property.

Police used some chemical irritants to break up the crowd. Initial reports said about 100 were actually causing the trouble, and the rest were just watching.

University Vice President Pam Wheelock said if things escalate this time around, onlookers should leave.

"There are no bystanders or spectators in a riot or a disturbance," Wheelock said. "If you are here, you are part of the incident, and you are subject to arrest."

Nine university students were arrested for disorderly conduct and unlawful assembly after the North Dakota game. The incident was over by 1:30 a.m., Wheelock said. No one was seriously injured, but a couple of officers did go to the hospital.

Police are gearing up for more potential disturbances Saturday. Wheelock said about 300 law enforcement officers will be patrolling Dinkytown after Saturday's Frozen Four final.

"We've done our homework and have researched what's going on in other communities where they've had teams playing," said Minneapolis Police Spokesman John Elder. "And we've come up with contingency plans for just about everything that could come our way."

According to university policy, the U of M can discipline students, which could be a warning or as harsh as expulsion, if they're involved in rioting near campus in response to a university-sponsored event.

The university is also asking non-students not to come to the area to join in any partying. If the Gophers win, the university will stage an official celebration sometime next week.

Minneapolis City Councilman Jacob Frey told reporters, "You don't score extra points by being an idiot after your team has already won the big game."