A one-year-old boy is undergoing surgery after he and seven others were wounded in a hail of gunfire along a California street, relatives said.

Oakland police Lieutenant Robert Chan told KTVU-TV the boy was possibly shot in the head and was in critical condition.

Police said the victims were taken to the hospital by others at the scene before officers arrived.

Investigators found dozens of bullet casings near the parking lot where the crowd had gathered.

Oakland police spokeswoman Johnna Watson said the shootings happened just after 6pm local time in the city's West Oakland neighbourhood.

The other victims' conditions were unclear, though their injuries did not appear life-threatening.

Police were seeking multiple shooters, but further details on suspects or a motive were not immediately available.

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