The turmoil erupted after a Los Angeles Fire Department inspector determined the theater was overcrowded, department spokesman Brian Humphrey said.
Police estimated about 2,000 people were inside the theater to catch the premiere of a documentary about the Electric Daisy Carnival rave. An unknown number of people were pushed out into the streets, joining a growing crowd that may have been drawn to the event from a Twitter message by a popular DJ known as Kaskade who said there'd be an accompanying block party.
Officers ordered hundreds of people to disperse, but the crowd refused and began throwing objects, Officer Karen Rayner said. Additional officers were called to the scene and were able to control the crowd several hours later.
""There were people trampling all over the police cars, smashing the windows," said Greg Magda, who works at a coffee shop on Hollywood Boulevard.
Two people were arrested for investigation of felony vandalism; three police cars were damaged, Rayner said. No injuries were reported.
A section of Hollywood Boulevard was shut down and a subway station under the famous theater and the next-door Hollywood & Highland entertainment complex was closed during the disturbance.
Kaskade, who in featured in "Electric Daisy Carnival Experience" and has more than 90,000 followers on Twitter, posted a tweet Wednesday afternoon inviting fans to the party."Today(at)6pm in Hollywood (at)Mann's Chinese Theatre. ME+BIG SPEAKERS+MUSIC(equals)BLOCK PARTY!!! RT! `' He also posted a photo of a flatbed truck with giant speakers that he was riding in to get to the block party.
He pulled up about 6:30 p.m., an hour before the premiere was set to begin, the Los Angeles Times reported, drawing a crowd that filled the middle of the street.
He later sent tweets urging peace.
"Everybody CHILL OUT!!! The cops are freaking out. BE SAFE AND LET'S HAVE SOME FUN!" he wrote. The DJ was scheduled to appear at a party after the screening.
Eyewitness video posted on Twitter showed police in riot gear firing non-lethal beanbags to tame the crowd.
Pasquale Rotella, whose Insomniac Events promotion company puts on the annual electronic music festival, said the block party had nothing to do with the film premiere.
"The crowd issues that arose were a result of individuals responding to social media information, which mistakenly led them to believe they could see artists perform," Rotella said in a statement.
He said the street closure caused him to miss the premiere of a film that he produced.
Elvin Romero said he came to listen to Kaskade after he saw the event listed on Facebook.
"There were just people chilling in the street," Romero said. "It all just got out of hand. Police tried to clear them out and that's when the trouble happened."
Ryan Hoepfner, 14, of Gainesville, Texas and his stepfather Mike Cooper watched the disturbance unfold across the street, from the eighth floor of the Roosevelt Hotel.
Hoepfner said there were several hundred people in the street, some wearing lingerie and elaborate chandelier hats when it appeared that a fight broke out.
"There was a fight in the middle. Then ... people started throwing stuff," Hoepfner said.
The rave was the focus of controversy in Los Angeles after a 15-year-old girl died of a drug overdose at the two-day event held in June 2010 at the Los Angeles Memorial Coliseum.
The death prompted officials to issue a brief moratorium on raves. Insomniac moved the event to Las Vegas this year.