Nine people have died following a shooting at a business premises in the Californian city of Monterey Park, police said.
The incident happened at about 22:20 local time on Saturday (06:20 GMT on Sunday).
Thousands of people had earlier gathered in the city for the Monterey Park Lunar New Year festival.
Police have not yet said how many people were injured in the shooting, or if they have made any arrests.
The Los Angeles County Sheriff's Department said the suspect in the shooting is male.
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Videos on social media showed a large police presence in the city, which is located about eight miles (13km) east of Los Angeles.
An eyewitness told the Los Angeles Times that three people ran into his restaurant and told him to lock the door as there was a man with a machine gun in the area.
The annual Lunar New Year festival is a weekend-long event that has previously drawn crowds of more than 100,000 visitors.
Saturday night's festivities were scheduled to end at 21:00 local time.
Monterey Park has a population of about 60,000 people and is home to a large Asian community.
Source: BBC