Large crowds gathered outside a complex of residence halls at UMass Amherst Wednesday night to celebrate the Red Sox victory in the World Series. But after students started climbing trees and throwing trash, police used loud speakers to direct the crowd to disperse.

A “raucous celebration” turned into a “disturbance,” according to university spokesperson Ed Blaguszewski. He said police used “pepper ball” and one “smoke grenade.”

A UMass statement said 15 arrests were made, but no injuries were reported. Most were charged with failing to disperse, but two were also charged with assault and battery on a police officer. All but one of those arrested are UMass students, the statement said.

UMass had set up activities, including free food, outdoor video screens and bouncy houses to try to avoid the types of disturbances – including riots – that have occurred at the university following past major sporting events.

“One inflatable amusement was damaged,” the university statement said.

UMass estimated that by the end of the game, 3,000 people showed up at the Southwest dorm complex.

“Most of the night was actually wonderful,” Blaguszewski said. “Clearly, if we’re making arrests, it’s a disturbance. But on relative scale on what has happened in the past, this is not on the same scale.”

New England Public Radio’s Susan Kaplan and Sam Hudzik contributed to this report.