Thousands of partiers and college students took to the streets in Berkeley near the Cal campus on Saturday night and early Sunday morning as Halloween revelry devolved into a massive riot.

Up to 5,000 people were in the streets near Channing Way and Piedmont Avenue, with some throwing rocks and bottles. At least one person was sent to the hospital as the result of three reported assaults. At this point it is unclear what sparked the chaos, though Berkeleyside reports that large parties were getting shut down by the Berkeley Fire Department after 10 p.m. Saturday night. There are several fraternities in the area, and earlier that day was a college football game at Memorial Stadium between Cal and USC.

Police responded to the area of Channing Circle after reports of a crowd of thousands throwing rocks and bottles, but no use of force by police—such as tear gas or batons—was reported. Lieutenant Alyson Hart of the Berkeley Police Department said the crowd had "thinned considerably" by 1:10 a.m., Sunday morning.

Despite the massive gathering and the objects being thrown by people in the crowd, police say there was only one confirmed case of property damage—a smashed car on Channing Way.

"There were a lot of people, and some of those people chose to act unlawfully," Lt. Andrew Rateaver told The Daily Californian. "Overall, that was a small portion of the people, and certainly not the entire group."

Captain Andrew Greenwood told Berkeleyside that at least three suspects had been arrested in connection with the three assaults, and that authorities believe that all three were responsible for the attacks. According to ABC 7, one person is in the hospital with a head injury. Records from the Alameda County Sheriff's Department show that as of 5 a.m., Sunday morning, three people had been booked: one for misdemeanor battery, one for a DUI, and another for public intoxication.

There were reports of supposed gunshots, but police were heard over the scanner saying they believed they were fireworks.