10 killed in mass shooting at Chinese New Year event near Los Angeles (Photo AP)

Ten people were killed and at least 10 others were injured when a gunman opened fire at a ballroom dance studio in Monterey Park on Saturday night, where a crowd of tens of thousands were celebrating the Chinese Lunar New Year, the Los Angeles County Sheriff’s Department said.

There was scant information on the gunman: male and still at large. There is no known motive, nor a description of the shooter. A law enforcement source briefed on the matter said the gunman used a high-powered assault rifle at close range.

Journalists from the news agency AFP - who were at the scene - said there was a large police presence and areas had been sealed with helicopters overhead.

"Our hearts go out to those who lost loved ones tonight in our neighboring city, Monterey Park…" Los Angeles City Controller Kenneth Mejia tweeted.

Mass shootings are recurrent in the US - the country with the highest rate of private gun ownership in the world. The deadliest shooting in California history was in 1984 - 21 people were killed at a McDonald's restaurant in San Ysidro.

Over 44,000 died of gunshot wounds last year; more than half were suicides.