Rocks, bottles and even lawn chairs were used as weapons in riots outside Dave Matthews Band concerts over the weekend in Hartford, Conn., that saw dozens of people injured, about 50 arrested and at least one car flipped and set ablaze, police said.

Police fired rubber bullets and pepper spray in an attempt to control angry music fans wielding broken glass.

"You'd hear the [pepper spray] gun go off and then you'd see the cloud," said concert-goer Thomas Quigley, 20, of Old Lyme, Conn. "Then the tough guys would start throwing bottles at police."

Quigley was arrested for trespassing and disorderly conduct during the first incident Saturday, he said, when he tried to enter the concert venue after losing his ticket.

Police blamed the riots outside the Meadows Music Theatre on dozens of people whom they say spent hours drinking and using drugs in a nearby parking lot. Many of those individuals had no intention of attending the jam-rock band's performance, investigators said.

"There seemed to be a significant number of people who came just to party," Hartford police Sgt. Neil Dryfe said Monday (Aug. 9).

Quigley, who ended up attending the Sunday show, backed up officials' observations. "Everyone was having a great time getting wasted," he said.

Members of the police department's Disorder Control Team fired rubber bullets at rioters who were attacking them Sunday, Dryfe said, explaining that some rioters tried to attack police with broken bottles. He could not say how many bullets were fired.

Tom Bevacqua, a spokesperson for the Dave Matthews Band at Red Light Management, said he was unaware of any other such violent behavior at the group's previous concerts and declined further comment.

A source close to the band said Monday that it was unclear whether Matthews knew about Saturday's melee by the time he performed Sunday. The source, who requested anonymity, said Matthews did not mention the disturbance while onstage.

Two weeks ago, the 30th anniversary Woodstock festival in Rome, N.Y. — at which Matthews played — ended in a fiery riot. About 500 state police were called to quell thousands of rowdy concert-goers who burned 12 trailers, looted from vendors and vandalized concert equipment. Police continue to investigate the incident, during which seven people were arrested, 60 were injured and which caused as much as $1 million in property damage.

Matthews fan Pete Monaco, who returned to his car after Sunday's show to find the windows smashed, was particularly surprised that such a disturbance would happen at a show by Matthews. The South African-born singer is known for his laid-back sound, which generally attracts a peaceful crowd, similar to that for neo-hippie band Phish.

"It shouldn't happen at a Dave Matthews Band concert," he said. "The music's not about that."

On Saturday, firefighters encountered a hailstorm of rocks and bottles when they attempted to extinguish a Toyota that had been rolled over and torched, Dryfe said. They finally quenched the blaze after breaking through with a police escort.

In all, during Matthews' three-night stand 55 people were arrested for a variety of offenses, including rioting, inciting to riot, assault on a police officer and breach of peace, Dryfe said. The trio of shows began with a peaceful performance Friday. Some of those who were arrested over the weekend were local residents, while others came from as far away as Arizona and Florida, he said.

Some arrests were for possession of nitrous oxide, or laughing gas, a drug whose prevalence in the parking lot helped spark the uproar, Dryfe said. At least one dealer sold hits of the gas from tanks in the back of a pickup truck, Dryfe said.

Inside the 25,000-seat open-air venue, police said they encountered few problems.

Monaco, 20, said he and three friends left Sunday's show after the final encore of "Don't Drink the Water" (RealAudio excerpt) and waited at a nearby McDonald's restaurant for traffic to subside.

When they reached the scene of the riot in the parking lot outside the shuttered Hartford Jai Lai Fronton, Monaco said he saw five officers in riot gear, two young men in handcuffs, and his 1988 Toyota Corolla, minus two backdoor windows that had been smashed out.

"I don't understand," said Monaco, who drove three hours from Long Island, N.Y., for the show. "I don't go to vandalize stuff."

Dozens of music fans suffered cuts and bruises, either from being knocked to the ground, or from falling in the parking lot blanketed with broken glass, Dryfe said.

Police have not pinpointed specific incidents that may have ignited either night's riot.

"Once it starts, a mob mentality takes over," Dryfe said.

Vandals slashed tires and broke windows on dozens of cars over both nights, and rioters tried to burn a portable toilet Sunday, Dryfe said. Police estimate the riots caused tens of thousands of dollars in damage. The incident is still under investigation.

Since his breakthrough third album, Crash (1996), Matthews has built a devoted following with improvisational shows that highlight his unusual vocal style, eclectic rhythms and sounds from instruments such as saxophone, violin and flute.

"It's mind boggling," said Gary Bongiovanni, editor of the concert trade magazine Pollstar, trying to understand how Matthews' fans could have become involved in the violent behavior police say occurred outside the venue.

Most of the melee on both nights occurred in the lot of the former Jai Lai venue, although it also spread to other lots. Dryfe said. Meadows leases the lots for concert parking. A Meadows staffer said the Jai Lai lot is rented from the city of Hartford. A spokesperson for Mayor Michael Peters did not return calls.

Though he won't give up his affection for Matthews' shows, Monaco has no doubts about seeing the him again at the Meadows.

"I'll definitely never go there again," he said.