HUNTINGTON BEACH, Calif. — A birthday party invitation that went viral on TikTok brought hundreds of people to a raucous celebration on a Southern California beach Saturday night, prompting police to declare an unlawful assembly and arrest nearly 150 people after they refused orders to disperse.

The massive gathering began with a now-deleted video posted on the popular social media app from a user named adrian.lopez517, who invited anyone to his birthday party by Huntington Beach’s fire pits Saturday night, The Orange County Register reported Sunday. The hashtag “AdriansKickBack” received more than 180 million views on TikTok.

One partygoer told a New York Times reporter: “It’s the first lit party since COVID.”

At least 400 people showed up to a pre-party Friday evening around a lifeguard tower, police Lt. Brian Smith said. When people in the crowd began to launch fireworks near the fire pits, he said, officers declared an unlawful assembly and the partygoers scattered.

Huntington Beach’s police department announced the next day that they were preparing for a surge of visitors due to the promoted party and warned that they will enforce local rules, including no alcohol or drug use on the beach and no fireworks.

But an even larger crowd overtook the beach Saturday evening. Police estimated that at least 2,500 people gathered at the beach before moving to the downtown area. Videos posted on social media showed fistfights breaking out, people jumping from the Huntington Beach Pier’s pedestrian bridge to a cheering crowd below, people jumping atop slow-moving cars and shooting more fireworks.

Officers again ordered the crowd to disperse and issued an overnight curfew as they received backup from other law enforcement agencies. Video footage shows officers dressed in riot helmets shutting streets to control the crowd and, in some instances, firing less-lethal rounds. Police said some people threw bottles, rocks and fireworks at officers.

A woman dining at Duke’s Hawaiian restaurant by the pier said she heard fireworks while she was eating, and when she went to the window to see what was happening she saw hundreds of people running away from the beach.

“People climbing walls and screaming, more and more fireworks, mobs running. They were asking us to let them in the restaurant, banging on the windows,” Sonya Gronning said. “When we went to leave there was a wall of police protecting the restaurant.”

The people arrested included 121 adults and 28 juveniles who were booked for vandalism, illegally setting fireworks, failing to disperse and violating curfews, said police spokeswoman Jennifer Carey.

A number of downtown businesses, police vehicles and a lifeguard tower were damaged, but no significant injuries were reported, she said.

Huntington Beach, which connects a vibrant business district to an 8-mile (13-kilometer) stretch of sand, has been the site of large gatherings in the last year as pandemic-related restrictions, the 2020 presidential election and the Black Lives Matter movement drew protesters who sometimes clashed with police in the downtown area.

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Nguyen reported from Oakland, Calif.