The collision occurred just before 8 p.m. at Highway 20 and Howard in Nice, according to the California Highway Patrol.
Initial reports indicated a vehicle struck a child on a bicycle.
REACH air ambulance lifted off at about 8:44 p.m. en route to Children's Hospital of Oakland, according to the CHP.
No other information was available late Wednesday.
Harold La Bonte contributed to this report.
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