Last week, we reported that a big Spring Break beach party on Isla Vista, close to University of California – Santa Barbara, devolved into a riot during which  100 were arrested and many were injured.

An investigation into the incident has not revealed the cause for the violence.

With the Deltopia riot come and gone, the University of California – Santa Barbara (UCSB) is left wondering what started the whole ordeal.

According to the Associated Press, debris from the annual party was still on the street Sunday and no one had come any closer to figuring out what caused the violence to erupt. Deltopia is a party that happens every year at UCSB, a known party school, but brick tossing, smashing bottles and throwing rocks are not typical traditions.

The school does not sanction Deltopia but it is still a well-known annual event to UCSB students. It was originally called “Floatopia” and it was held on the beach. In 2009, the party was banned and the beaches have been closed every year since.

Still, Deltopia occurs at the same time every year, the first weekend of the spring quarter, only now it is held inland. Thanks to the excessive violence of this year’s party, Deltopia and all large college parties are in more danger than they ever have been.

“That doesn’t happen, especially here,” Jake Pangburn, a 21-year-old senior who lives near where the riot began, told the AP.

With nearly a quarter of a million people attending Deltopia this year, politicians, school leaders and other authorities will try to make sure it never happens again.

“Students historically get together and party,” State Sen. Hannah-Beth Jackson told the AP. “But it’s not as extreme as what we saw on Saturday.”

The party turned into a riot around 9:30 p.m., authorities said, when a student struck a police officer in the head with a bag full of liquor bottles. The officer was trying to break up a fight, but what ensued was much worse.

The mob began hurling bricks and rocks, tearing down street signs, smashed windows and tipped cars. Police had to resort to using force to break up the riot, bringing in armored vehicles, firing rubber bullets and tossing tear gas containers.

The Santa Barbara Sheriff’s Office said 16 of the 62 people given citations were actually students at UCSB, meaning much of the madness was likely caused by visitors.

Knowing full well the party will go on next year, UCSB officials are holding meetings with students to figure out a way to ensure Deltopia 2015 is held safely and without major incident.