Dozens were injured and 100 were arrested when a massive party in Santa Barbara, Calif., known as Deltopia devolved into a violent riot on Saturday night.

Deltopia is an unofficial annual event held in the Isla Vista community. Many who attend are students from the University of California at Santa Barbara and other surrounding schools. About 15,000 people showed up at Deltopia on Saturday.

The unrest began when sheriff’s deputies responded to a report of two stabbings at around 8 p.m. People started throwing bricks, bottles and rocks at the officers in protest. An officer made an arrest are being hit with a bag filled with bottles.

Police called in backup and the crowd became more unruly. People smashed and stomped a car parked on the street, tore down street signs and lit trash and a mattress on fire.

Police used tear gas, pepper spray and rubber bullets to clear the crowd. This is what it looked like:

The crowd was broken up at about 1 a.m., but not before state and private property was destroyed, five officers were injured and 26 people were sent to the hospital. At least 14 were hospitalized for alcohol-related injuries, including alcohol poisoning.

Local media outlets speculate that the crowd was already upset because police preemptively banned music at Deltopia, since it's not a city-sanctioned event. A student at UC Santa Barbara who attended the party said police efforts to keep the party in check likely frustrated people who came from far off. According to KEYT-TV, some people traveled from as far as Nevada and Arizona.

“I feel like these out-of-towners came in expecting music and dancing in the street, and when they didn’t get that, they started tearing out stop signs,” said the student to KPCC, a local NPR affiliate.

An 18-year-old California Polytechnic State University study was killed at last year’s Deltopia after falling from a 60-foot cliff in Isla Vista. Deltopia got started in 2010 when Santa Barbara County shut down beaches to stop its predecessor, Floatopia, which left Santa Barbara’s beaches strewn with trash. Along with at least 100 people arrested on Saturday, 36 people were arrested and 88 citations were given out Friday night.