At least ten people were hospitalized after the shooting spree.
Tehama County Assistant Sheriff Phil Johnston stated that the shooter was "randomly picking targets". He wrote: "My mom just called me, there was a shooting at my little brother's school, 2 kids have been shot, parents are dead, my mother saw this and was in the middle of it". Officials said they are actively searching for the shooter. "They went around the community shooting at the schools!"
Mr Johnston said police were alerted to the shooting at around 8am local time (4pm GMT).
Remington manufactured the military-style assault rifle used in the 2012 massacre at Sandy Hook Elementary School that killed 20 children and six adults.
Johnston said the gunman, apparently frustrated, left the school grounds and resumed his random shooting before crashing the vehicle.
All other students had been evacuated from the school, authorities said.
He said the suspect has been identified, but his name has not been released pending notification of next-of-kin.
"There was an active shooter out there earlier this morning", said Jeanine Quist, an administrative assistant with the Corning Union Elementary School District.
Flint says he had been shooting "hundreds of rounds" from large magazines.
Reporter Sara Stinson, calling Action News Now from the police roadblock, told the news channel there is a shot-up, taped-off truck on the road, and several anxious parents unable to get past the roadblock and struggling to find a cellphone signal.
Rancho Tehama resident Salvador Tello, who was taking his three children to school, described seeing the gunman open fire, killing a woman.
Another witness, Casey Burnett, said the gunman was "driving around and shooting randomly from his vehicle".