The shooting happened around 11:15 a.m. at Oxnard's Christa McAuliffe Elementary School.
Investigators say there was a car-to-car shooting near the school and a girl was struck on the playground during recess.
"We thought it was firecrackers or Pop-Its at first," student Isaiah Bustamante said. "Then all of us started getting all freaked out. We ran inside to the hallways, we ran to a classroom. We turned off all the lights and we hid for a while, for 10 or 20 minutes."
The school went into lockdown as students and faculty sheltered in place.
The student's injury was described by officials as non-life-threatening.
"The students and faculty were sheltered in place," said Oxnard Police Chief Scott Whitney. "Officers arrived, they checked the school. As quickly as we could, we went through the campus to make sure there was no other threat and no other injured students."
The girl's parents were notified and joined her at the hospital.
Other parents were notified and lined up at the school to pick up their children.
"The child's parents have been notified by the Oxnard School District, and all other students have been accounted for and are safe," police said in a statement.
Police were continuing to look for two suspects and no descriptions were immediately available.