It started with a DJ's simple tweet telling his followers about a free block party on Hollywood Boulevard.
Evidently, too many people got the message and the Wednesday night party quickly got out of hand.
The tweet lured thousands of raucous ravers to hear DJ Kaskade spin some tunes outside Grauman's Chinese Theatre, the landmark cinema in the heart of Hollywood where stars press their shoes and handprints into cement slabs.
The movie theater was hosting the premiere of the documentary "Electric Daisy Carnival Experience" about a popular series of raves that were banned in Los Angeles after a teen died of a drug overdose. The film features Kaskade, whose real name is Ryan Raddon.
"He just wanted to do something for the fans," Alastair Duncan, a spokesman for the DJ, said Thursday.
Duncan said Raddon had a permit from the Fire Department to play a free show and to close off one traffic lane for his flatbed truck bedecked with enormous speakers.
Michael Duddie, general manager at the Supperclub, which hosted Kaskade at an after-party following the premiere, said he saw the truck get hemmed in by people as it tried to make its way to the theater.
"He couldn't get two blocks," Duddie said. "Within three minutes, there were 1,000 people and within five minutes there were 3,000."
Duddie saw the truck veer down a side street, followed pied-piper style by hundreds of ravers.
Without music, crowds outside the cinema grew restive and found themselves facing baton-wielding riot police. Three people were arrested after things turned rowdy, with would-be revelers hurling bottles at police and some jumping on a squad car.
Police and city officials were investigating what prompted the unruly crowd to gather. It was too early to say if Kaskade would face any legal action by authorities, city attorney spokesman Frank Mateljan said.
The crowds gathered soon after Kaskade tweeted: "ME+BIG SPEAKERS+MUSIC(equals)BLOCK PARTY!!!"
He apparently underestimated the appeal to his more than 92,000 Twitter followers. By 6 p.m., hundreds of people had gathered outside the cinema and were spilling onto the street. Police and fire officials soon closed the boulevard to traffic.
"They showed up because, allegedly, the DJ tweeted he was doing a concert," fire Battalion Chief Michael Bowman said. "People's expectation was they thought they were going to a free concert in the street."
Kaskade later sent tweets urging peace.
"Everybody CHILL OUT!!! The cops are freaking out. BE SAFE AND LET'S HAVE SOME FUN!" he wrote.
Kaskade was on a plane to play a show in Spain and could not be reached for comment Thursday.
Duddie said the after-party crowd at Supperclub was smaller than expected because people had a hard time getting to the venue.
"Some of our VIP clients who intended to come to the party thought it might be a little too much drama considering what was unfolding," he said.
Many residents reacted angrily to the near-riot. Facebook users flooded Kaskade's page with negative comments about how their commutes had been delayed or their visits to the area had been ruined.
Duddie thought the invitation by Kaskade was well-intentioned but had backfired.
"The spirit of it was a great idea," he said. "It's unfortunate an act of fun was marred by a few people who don't understand basic civil courtesy."
One person was arrested for felony vandalism after a police car's windshield was smashed and its door dented. Another was taken into custody for hitting a police officer, and a third was nabbed for failing to disperse.
"There were people trampling all over the police cars, smashing the windows," said Greg Magda, who works at a coffee shop on Hollywood Boulevard.
That street and two others were closed for hours while police tried to get ravers to disperse. Some in the crowd threw bottles at police, but others were playful.
Some ravers "planked" in front of riot officers — an Internet-driven phenomenon in which people lie face down in improbable places while their friends snap pictures.
Police were bracing Thursday for another large crowd in Hollywood, where Lady Gaga was scheduled to perform in a parking lot near the theater that hosts ABC's "Jimmy Kimmel Live." But the performance went smoothly and no problems were reported, police said.
The melee outside Grauman's was the latest music-related disruption in Southern California.
In October, members of the Orange County band Imperial Stars climbed atop a truck that stopped on U.S. 101 near Sunset Boulevard. Three members of the band, which performed a song called "Traffic Jam 101," have pleaded not guilty to conspiracy, creating a public nuisance and other charges. They could face up to three years in prison if convicted.
The Electric Daisy Carnival is the largest electronic music party in the U.S.
After it was banned from Los Angeles, it moved to Las Vegas. At an Electric Daisy event in Dallas in June, a 19-year-old man died and more than two dozen people were treated at hospitals for drug, alcohol and heat-related problems.
Watkins can be reached at http://twitter.com/thomaswatkins