An annual spring break party in Southern California turned into an all-out brawl Saturday night, during which multiple people were arrested and even more hospitalized.

The squabble began at 9:30 p.m. in the town of Isla Vista after a UC Santa Barbara police officer was hit on the head at the Deltopia party, attended by approximately 15,000 people, with a backpack containing several large bottles of alcohol, according to a statement on the Santa Barbara County Sheriff's website. Officers arrested 18 people during the disturbance, while nearly 30 were taken to the hospital.

After the initial incident, the violence escalated. A large crowd amassed over several blocks and threw rocks, bricks and other objects at officers. At least five more officers were injured during the disturbance. One took a blow to the face from a brick and two others were hit on their hands with bottles. All of the injured officers were released from the hospital Sunday morning, the Associated Press reports.

Tear gas and foam projectiles were used to handle the crowd, which also tore stop signs out of the ground, ignited small fires and damaged law enforcement vehicles.

"Our community is really in disbelief and shock over what we witnessed last night," Kelly Hoover, a spokesperson for the County Sherriff's Office, told Mashable. "I think there will be a great deal of dialogue between community leaders and the public."

Many Deltopia party-goers posted messages about the incident on Twitter, while others expressed frustration concerning the disturbance.

My night consisted of Tear gas , flash bangs, police shooting kids with rubber bullets, and a crazy riot. #deltopia

— Nick Wehrli (@NickWehrli182) April 6, 2014

I literally can't believe I survived Deltopia holy shit

— ♡ Amanda Eckford ♡ (@pandaisurbannnn) April 6, 2014

Stampede running from tear gas and rubber bullets! #Deltopia #Deltopia2014 #IslaVista #SantaBarbara… http://t.co/P0SnEQtVeJ

— Lauren Billings (@LBillings247) April 6, 2014

And concerning Deltopia, wth you out-of-staters, can't you just go to Vegas instead

— Xander Reyes (@Xandarrrrrgh) April 6, 2014

Being associated with the riots and damage caused by Deltopia is humiliating. The ridiculous lack of respect disgusts me.

— Alex (@alexsutter) April 6, 2014

Deltopia is an unsanctioned event, according to Hoover. Originally called Floatpia, and held at a nearby beach, the event was shut down in 2009 due to reoccurring problems such as water rescues and environmental concerns.

Since then, the event has moved to the streets, but the problems have persisted. During last year's event, a woman died falling off a cliff, Hoover said.

Order at this year's event was only restored after several hours, with officers still present in the area Sunday morning. According to the AP, more than 100 people were arrested and nearly 50 hospitalized.

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