Update 8.30am: A Northern California man killed two neighbours with whom he had been feuding before he went on a shooting rampage at apparent random sites -including an elementary school, officials have said.
Two more people were killed and 10 injured before police fatally shot him.
Police said surveillance video shows the shooter unsuccessfully trying to enter a nearby elementary school after quick-thinking staff members locked the outside doors and barricaded themselves inside when they heard gunshots.
Tehama County Assistant Sheriff Phil Johnston said the gunman spent about six minutes shooting into Rancho Tehama Elementary School before driving off to continue shooting elsewhere. Mr Johnston said one student was shot and injured and is expected to survive.
"It was a bizarre and murderous rampage," Mr Johnston said.
He said the 45-minute spree ended when a patrol car rammed the stolen vehicle the shooter was driving and killed him in a shootout. Mr Johnston said the shooter was facing charges of assaulting one of the feuding neighbours in January and that she had a restraining order against him.
"I think the motive of getting even with his neighbours and when it went that far - he just went on a rampage," Mr Johnston said. He said there was a "domestic violence" report on Monday involving the gunman, but did not provide any further details.
At least one of the victims has life-threatening injuries, he said.
Mr Johnston declined to identify the shooter until his relatives were notified, but he confirmed the gunman was charged with assault in January and had a restraining order placed against him. The district attorney, Gregg Cohen, told the Sacramento Bee he is prosecuting a man named Kevin Neal in that case.
Neal's mother told The Associated Press he was in a long-running dispute with neighbours he believed were cooking methamphetamine.
The mother, who spoke on condition she be named only as Anne, lives in Raleigh, North Carolina, where she raised Neal. She said she posted his $160,000 bail and spent $10,000 on a lawyer after he was arrested in January for stabbing a neighbour. Neal's mother said the neighbour was slightly cut after Neal grabbed a steak knife out of the hand of the neighbour who was threatening him with it.
She wept as she told how she spoke to Neal on the phone on Monday.
"Mom it's all over now," she said he told her. "I have done everything I could do and I am fighting against everyone who lives in this area."
She said Neal apologised to her during their brief conversation, she thought for all the money she had spent.
He also told her that "Mom you know what, my whole life you gave me such a good happy life and nobody could have a better mother than I had."
Then he said: "All of a sudden, now I'm on a cliff and there's nowhere to go. No matter where I go for help here I get nobody who will help me. All they are doing is trying to execute me here."
Neal's sister, Sheridan Orr, said the family was trying to reach the sheriff's department last night but still had not been notified. She said her brother had struggled with mental illness throughout his life and at times had a violent temper.
"We're stunned and we're appalled that this is a person who has no business with firearms whatsoever," Ms Orr said. "Our deep, deep sympathy for the victims and it sounds trite but our hearts are breaking for them."
Mr Johnston said officials received multiple 911 calls about gunfire at an intersection of two dirt roads. Minutes later, more calls reporting shots flooded in from different locations, including the school.
Witnesses reported hearing gunshots and children screaming at the school, which has one class of students from kindergarten through fifth grade.
Mr Johnston said the shooter was armed with a semiautomatic rifle and two handguns at seven locations. He said another weapon was seen in one of the vehicles he drove but had not been recovered yet.
Update 10.30pm: A gunman choosing targets at random opened fire in a rural California town, killing four people at several sites and wounding others at a primary school, before police shot him dead, authorities said.
The gunfire began at about 8am in the community of Rancho Tehama Reserve, about 130 miles north of Sacramento.
"It was very clear at the onset that we had an individual that was randomly picking targets," Tehama County assistant sheriff Phil Johnston said.
Witnesses reported hearing gunshots and children screaming at a primary school about five miles down a road from where the shooting is believed to have started.
Several people were wounded at the school, said Jeanine Quist, an administrative assistant with the Corning Union Elementary School District.
Salvador Tello said the gunman fired at a truck in front of him as he was dropping off his three children.
Mr Tello said he was close to the school when bullets made "big holes" in the truck in front of him.
He said he forced his children to duck down and slammed his truck into reverse and headed to the children's grandmother's house.
"I put my kids down and put my truck in reverse and went out," he said.
"I don't believe it, because I wake up, take my kids, feed them cereal and put them in the truck, and say 'let's go to school like a normal day'."
On the way, he said, he saw an apparent gunshot victim and police at another scene.
Details were still sketchy hours after the shootings, and authorities did not have a firm count of the wounded due to the number of places the gunman attacked, Mr Johnston said.
Authorities recovered a semi-automatic rifle and two handguns.
The rural area is described on its website as a "quiet private country community" where "the people are friendly and the pace is relaxed".
Two hospitals said they were treating a seven gunshot victims, including at least three children.
At least one child was wounded at the school. Another child was shot while driving with a woman, who also was wounded, Mr Johnston said.
He declined to release the name of the gunman but said he was "aware" of a domestic violence incident that neighbours reported.
Brian Flint told the Record Searchlight newspaper in the city of Redding that his neighbour, who he knows only as Kevin, was the gunman, and that his roommate was among the victims. He said the gunman also stole his truck.
"The crazy thing is that the neighbour has been shooting a lot of bullets lately, hundreds of rounds, large magazines," Mr Flint said.
"We made it aware that this guy is crazy and he's been threatening us."
Update 7.45pm: A series of shootings in rural northern California have left five people dead - including the gunman, authorities say.
Two children were among the wounded, it was confirmed.
Tehama County Assistant Sheriff Phil Johnston said one child was shot at a school, and another was shot while riding in a pick-up truck with a woman who was also wounded.
Mr Johnston says the gunman was "randomly picking targets".
He said there were seven shooting scenes and that there may be more victims.
Investigators have recovered a semi-automatic rifle and two handguns.
California Governor Jerry Brown later said he and his wife, Anne, were saddened by the shooting that "shockingly involved schoolchildren".
Gov Brown offered their condolences to the families who lost loved ones and said they are united with all Californians in grief.
Earlier: Three people have been killed in shootings at multiple locations in rural northern California, and the gunman was killed by law enforcement officers, officials have said.
Students also were shot and wounded at a primary school.
Tehama County Assistant Sheriff Phil Johnston told a TV station in the city of Chico that officers are investigating at least five crime scenes in and around the school in Rancho Tehama Reserve, about 130 miles north of Sacramento.
Jeanine Quist, an administrative assistant with the Corning Union Elementary School District, says no-one was killed at the school, but a "number" of students were shot and wounded.