US authorities have appealed for help in finding the person responsible for a shooting that left four people dead, three of them children, at a birthday party at a banquet hall in California.
Spokesperson for the San Joaquin County Sheriff's Office Heather Brent said the children killed in the shooting were aged eight, nine and 14.
She said a 21-year-old also was killed in the attack during the party in the city of Stockton.
"This was a birthday party for a young child, and the fact that this happened is absolutely heartbreaking," Ms Brent said at a news briefing at the site.
The sheriff’s spokesperson said the search continues for possible suspects. No arrests have been made.
Faith leaders in the Stockton area were planning a Sunday afternoon vigil to honour the dead and pray for the 11 people who were wounded.
Local officials pleaded with the public for help. Detectives are working to identify a possible motive.
"If you have any information as to this individual, reach out immediately. If you are this individual, turn yourself in immediately," San Joaquin County District Attorney Ron Freitas said.
The shooting occurred just before 6pm inside the banquet hall, which shares a car park with other businesses. Stockton is a city of 320,000 about 64 kilometres south of Sacramento.
"This is Thanksgiving weekend. This is when families come together, celebrate, share memories, give each other love," Mayor Christina Fugazi said.
"Unfortunately tonight, heaven is a little bigger with the individuals, children and adults that unfortunately did not make it."
Ms Fugazi recalled a shooting several years ago in which "seven people were gunned down" in the city, adding that both attacks were "unacceptable".
"Stockton is better than this," she said.
Authorities did not immediately provide additional information about the conditions of the victims.
Officials said earlier that several were taken to hospitals.
"Families should be together instead of at the hospital, standing next to their loved one, praying that they survive," Ms Fugazi said.
There have been 504 mass shootings in the United States so far this year including the Stockton incident, according to the Gun Violence Archive - which defines a mass shooting as four or more people shot.
