Tehama County Assistant Sheriff Phil Johnston said that around one hundred law enforcement personnel were investigating five separate scenes relating to the incident.
Johnston said he was told the suspected shooter was killed by law enforcement gunfire.
Johnston said officials did not have an accurate count of the total number of people injured in the shooting that unfolded across at least seven locations. "This guy has been insane, and he's been threatening us and everything".
"I know that we have medevacked (airlifted) a number of students, I know that the school has been cleared, I know that we have the children that were attending school in a safe location at this time", Johnston said.
At least three children and one adult were brought to the Enloe Medical Centre, in Chico, California, the hospital confirmed to KHSL.
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The gunman was reportedly shot by police. Students also were shot and wounded at an elementary school.
Living near the gunman was "hell", Flint said, and the man was a known felon who often harassed him and his neighbors. Mercy Dignity Health confirmed that the hospital has received three patients.
Jason Wandel, chief division counsel at the FBI's Sacramento field office, told AFP that agents had been sent to help with the investigation but wouldn't confirm any details regarding the incident.
California Governor Jerry Brown said in a statement he and his wife were "saddened to hear about today's violence in Tehama County, which shockingly involved schoolchildren".
Matray says although the shooting occurred before school started, there were already kids on campus. "We offer our condolences to the families who lost loved ones and unite with all Californians in grief".