AMHERST, Mass. (AP) – University of Massachusetts officials are blaming a small group of students for inciting rowdy crowds after Red Sox victories, and campus police there and at other New England schools say they’re taking steps to prevent more outbursts.

Three students were arrested and charged with disorderly conduct and rioting after the Red Sox beat the Yankees in the first game of the American League Championship Series on Wednesday. Another three students were arrested in connection with damage done on campus after Boston beat Oakland on Saturday.

“The primary agitators are a group of about 100 people who have a mob mentality,” UMass police Chief Barbara O’Connor said Thursday. “It’s become a game to them.”

Similar incidents at campuses in Rhode Island and New Hampshire have officials there considering disciplinary action.

At UMass, one student was treated for injuries after being punched in the face Wednesday night, O’Connor said. There were no other reported injuries, and there was no property damage done on campus, she said.

After Wednesday’s game, a group of about 1,100 students at the 20,000-student campus were gathered around a bonfire. Some students were jumping through the flames, and others were dropping bottles and cans from dormitory windows, O’Connor said.

The crowd soon dwindled to about 450 students, and police broke the group up by throwing a harmless gas canister into the crowd, she said.

Most of the students then left the scene, but some were throwing bottles and rocks at campus police officers, O’Connor said.

She said security patrols would be increased on campus for Thursday night’s game. She estimated her department will spend about $30,000 in overtime to step up security during the series.

“This is an unexplained phenomenon that isn’t just happening at UMass,” O’Connor said. “It’s happening at other colleges in the area, as well.”

In New Hampshire, two Plymouth State University students were arrested and charged with criminal mischief and fueling a bonfire following Monday night’s Red Sox victory celebrations.

Crowds also gathered at the University of New Hampshire, where one student was arrested on a disorderly conduct charge.

Kim Billings, a spokeswoman for UNH in Durham, said student leaders were talking to students one-on-one in all residence halls and off campus apartments about celebrating responsibly.

“We all want a collaborative effort going into the weekend,” said Ann Weaver Hart, university president. “We will continue to work in close partnership with town officials to ensure that the campus and Durham community is safe.”

At Keene State College in Keene, N.H., 150 Red Sox fans took to the streets after Wednesday night’s win over the Yankees. College officials said police will have additional officers patrolling Thursday.

At the University of Rhode Island, officials are threatening disciplinary action following a raucous, student-led celebration Wednesday night that left three classmates injured and four students under arrest.

“What happened last night wasn’t about baseball. What happened last night was a relatively small group of students became performers and a relatively large group of students became the audience,” URI President Robert Carothers said Thursday.

Police and eyewitnesses said a car was overturned, and bonfires were lit, including one on the quad. Also, bricks were thrown through dormitory windows. Video footage showed dozens of students running around and screaming, and others milling around a fire.

“It’s just kind of like a scary scene, really ugly,” said Chad Anderson, a URI student.

At UMass, Matthew Stinson, a 25-year-old senior from Belchertown, said: “I guess I’m not really surprised. This place is insane. I feel alcohol is a big factor in all this, and I guess a lot of people don’t have a healthy outlet for their anger.”

AP-ES-10-09-03 1649EDT