The band have just released their second album

Six fans were arrested and police and crowd members were treated for minor injuries when fans rioted after fire officers called the performance off because the crowd was too big.

Angry fans rushed the stage and toppled speaker stacks before throwing missiles at police and breaking windows when the show was cancelled on Monday.

'Hostile crowd'

The band, who arranged the show to tie in with their latest album launch, never made it on stage and said they are "stressed out" by what happened.

System of a Down are making a name for themselves

Police Commander David Kalish said: "They were a hostile crowd. They were throwing rocks, bottles and debris at the officers and [mounted patrol] horses."

Glass doors and windows of nearby businesses were smashed, and part of Hollywood Boulevard was closed overnight.

About $30,000 (�21,000) worth of the band's equipment and instruments was taken or damaged, and journalists and TV news vans also came under attack.

The six arrests included charges for assault with a deadly weapon, grand theft and receiving stolen property.

The band, who have a strong following in their home town, have been gaining huge exposure ahead of the release of their second album, Toxicity.

"We're from Los Angeles and we wanted to give them kind of a hometown thank you," lead singer Serj Tankian said.

"But we're definitely overwhelmed and stressed out at how things turned out."

The band are about to co-headline an American tour with masked heavy rock band Slipknot, who are number one in the UK album chart.

System of a Down are currently building up their profile in the UK, and recently played on the main stage at the Reading and Leeds festivals.