Assistant Sheriff Phil Johnston told Redding.com that the suspected shooter was killed by law enforcement officers, and the number of dead may rise.
It said initial reports indicated the shooter had barricaded himself inside a building before being shot by police.
The AP reported that the shooter was killed by law enforcement after wounding some students at the school.
The Redding Record Searchlight said among the wounded was a six-year-old who suffered two gunshot wounds and another child shot in the leg. There are at least seven crime scenes related to the incident. Johnston said the school had been cleared by 10 a.m. but he did not have any information about the victims there.
Mr Johnston said police were alerted to the shooting at around 8am local time (4pm GMT).
Some students were transported to hospitals by helicopter, and others were moved to safe locations, the assistant sheriff's said.
Enloe Medical Centre spokeswoman Nicole Johansson said the hospital was treating four people this morning, including three minors.
The gunfire began around 8 a.m.in the community of Rancho Tehama Reserve, about 130 miles north of Sacramento.
While precise details about what led up to the shooting were unclear, Johnston said authorities were told by neighbors that "there was a domestic violence incident" involving the suspected attacker.
Investigators have recovered a semi-automatic rifle and two handguns. His neighbor's roommate indicated that the gunman may have stolen his truck, and that he had been shooting "hundreds of rounds", presumably near his house.