Three people were arrested in the crowd. One was arrested for felony charge of vandalism, and another was arrested for assaulting an officer.
Three separate events were held on the same street Wednesday night: Grauman's Chinese Theatre held a movie premiere about electronic dance music; an afterparty was scheduled at Supperclub at Vogue down the street; and one of the artists featured in the film, Kaskade, was performing a live show on the street, prompting a "flash mob"-type block party.
There was a movie premiere about the Electric Daisy Carnival rave, and then there was a free concert put on by DJ Kaskade. He tweeted to his 90,000 followers about the event, and a lot of his fans turned out.
DJ Kaskade was parading down Hollywood Boulevard to help promote the movie premiere at Grauman's Chinese Theatre. Things got out of hand quickly, and police moved in.
"I've never seen anything like this in real life, but I've seen it on TV, so I knew how bad it possibly could get," said Leila Velez, guest experience manager at Madame Tussauds Hollywood.
Police say hundreds of people poured onto Hollywood Boulevard, forcing authorities to close the roadway. Officers reportedly fired bean bags into the crowd when they refused to disperse.
Several police vehicles were damaged in the chaos, as police responded with riot gear to try to control the crowd.
No one suffered major injuries.
"People were kicking the windshields and breaking windshields," said bystander Sydney Williams. "It was crazy. And then the cops came and were shooting rubber pellets."
The LAPD will be looking at surveillance video to see if they can make more arrests related to the vandalism.
Insomniac Events, the organization behind the documentary, denied any involvement with the chaotic events in a statement.
"While this film showcased an Insomniac event, Insomniac had nothing to do with the supposed 'block party,' which was not a part of the premiere," the statement said. "Insomniac strongly believes in personal responsibly and hopes that anyone who didn't comply with police orders is held accountable."
Kaskade's publicist sent Eyewitness News an email stating that they did have a permit for the public performance. The LAPD denied that was true. The L.A. City Attorney's Office is investigating.
A Lady Gaga concert was scheduled for Thursday night on Hollywood Blvd. as part of her appearance on "Jimmy Kimmel Live!" Big crowds were expected for that event. The LAPD said police were prepared for Thursday night's event. About 2,000 fans were expected at Thursday night's event.