California -- Three children are among four people who died in a mass shooting at a child's birthday party in California, police have said.

The children who died were aged 8, 9 and 14, while a 21-year-old adult was also killed in Saturday evening's attack at a banquet hall in the city of Stockton, about 60 miles east of San Francisco.

Police asked the public for help tracking down the attacker, who has not been officially named. No arrests have been made.

Local faith leaders were planning to hold a vigil for the dead and wounded on Sunday.

Officers were called to a banquet hall in the incident just before 6pm local time (2am UK time).

"We can confirm at this time that approximately 14 individuals were struck by gunfire, and four victims have been confirmed deceased," the Sheriff's Office said on X.

The post said early indications suggest it could be a "targeted incident" but that information remains limited.

Police have so far not disclosed the attacker's identity and the motive is unclear.

Stockton's vice mayor Jason Lee confirmed on Facebook that the shooting on Lucile Avenue happened at a child's birthday party.

Mayor Christina Fugazzi said that "families should be together instead of at the hospital, standing next to their loved one, praying that they survive".

California governor Gavin Newsom's office added that he had been briefed on the "horrific shooting".