At least 10 people were killed and 10 others injured in an attack at Monterey Park, California, late Saturday, according to the Los Angeles County Sheriff's Department.
Several hours after the shooting, police said the suspect was still at large.
"The suspect fled the scene and remains outstanding," Captain Andrew Meyer of Sheriff's Department told reporters.
The shooting took place after 10 p.m. (0600 GMT) near the site of a Chinese Lunar New Year celebration that had been attended by thousands of people, the Los Angeles Times reported.
Footage posted on social media showed police cars at the scene, with several streets cordoned off.
Monterey Park, a city of about 60,000 people with a large Asian population, lies around 11 kilometers (7 miles) east of downtown Los Angeles.
"Our hearts go out to those who lost loved ones tonight in our neighboring city, Monterey Park, where a mass shooting justoccurred," Los Angeles City Controller Kenneth Mejia said in a tweet.
Saturday was the start of the two-day Lunar New Year festival, which is one of the largest in southern California.