Police are attending a taking pictures in Monterey Park, California, with a number of casualties, the Los Angeles Instances studies.
The taking pictures happened after 10pm (0600 GMT) close to a Chinese language Lunar New 12 months celebration in Monterey Park, the newspaper stated, citing native legislation enforcement.
It was not clear how many individuals had been injured or killed, or if the suspect was nonetheless at giant.
Tens of hundreds of individuals had attended the competition earlier within the day.
Footage posted on social media confirmed emergency workers treating casualties on the scene and police guarding cordoned-off streets.
The LA Instances quoted the proprietor of a close-by restaurant as saying that individuals who sought shelter in his property informed him there was a person with a machine gun within the space.
Seung Gained Choi informed the newspaper that he believed the taking pictures happened at a dance membership.
Monterey Park is a metropolis in Los Angeles county, about 11 kilometers from downtown Los Angeles.
