Four people died after 14 people were shot at a family gathering in Stockton in northern California on Saturday night, police said.
The shooting took place at a child's birthday party, Stockton's Vice Mayor Jason Lee said in a Facebook post.
"I am in contact with staff and public safety officials to understand exactly what happened, and I will be pushing for answers," he said.
Police said they received reports shortly before 6:00 p.m. local time (0600 GST) of a shooting that occurred near the 1900 block of Lucile Avenue in Stockton.
"We can confirm at this time that approximately 14 individuals were struck by gunfire, and four victims have been confirmed deceased," San Joaquin County Sheriff's Office said in a post on X.
"This is a very active and ongoing investigation, and information remains limited. Early indications suggest this may be a targeted incident, and investigators are exploring all possibilities."
Authorities have not provided any details about a shooter.

Putin says US-Russia contacts beneficial as talks begin with Witkoff and Kushner
Chinese national rescued from Nepal tunnel 10 days after flash flood
US envoys Witkoff, Kushner arrive in Moscow for talks on peace in Ukraine
One dead, 11 people missing after mudslide in China's Jiangxi province
Philippine VP Duterte posts bail after arrest order for alleged grave threats
Lindsay Clancy trial over killing her children ends in mistrial
Israel says it strikes southern Lebanon after Hezbollah drone launch
Sydney sweats in spring hot spell, faces 'extreme' bushfire risk
