The chaos in the streets began when police say a large crowd gathered at Main Street and Pacific Coast Highway after the popular surfing event. Police said that's when a large fight broke out.
When officers tried to break up the disturbance, the crowd moved into the downtown area of Huntington Beach. Witnesses say other fights broke out from there, and police said the crowds refused to disperse and began fighting and damaging property.
Photos and video showed small fires erupting in the streets and young men kicking down newspaper stands.
"People started getting a riot mentality, and things started getting crazy. And then on Main Street, people started pushing over Porta-Potties, jumping on the Porta-Potties, then they started breaking things in the street," said one witness.
Huntington Beach police requested help from other agencies to disperse the crowd, which was declared an unlawful assembly. Dozens of Huntington Beach police moved in and fired non-lethal ammunition at times.
Huntington Beach police say eight people were arrested and booked at city jail for failure to disperse.
Things had settled down by around 9 p.m. and streets were reopened. Police said damage was done to city vehicles, broken windows and street signs, and loss of property is still being determined. No injuries were reported, police said.