The alleged gunman was also shot dead by authorities, the sheriff’s department said.
There are also reports and eyewitness accounts of several people injured, while the sheriff’s department said some students had been airlifted from the scene.
Police in Tehama County, California, said the shooting began at a home in the local area and moved to Rancho Tehama elementary school.
Several shots were fired at the school, sometime before 9am.
There are currently 100 law enforcement personnel on the scene, while residents have been encouraged to remain in their homes as police investigate.
Assistant Sheriff Phil Johnston said: “I know that we have airlifted a number of students.
“I know that the school’s been cleared. I know that we have children that were attending school in a safe location at this time.”
Eyewitness Coy Ferreira told local media KRCR he was dropping his daughter off a kindergarten around 8am local time when the shooting began.
He said he heard what sounded like a firecracker before a school secretary ran out and told everyone to go into classrooms due to a shooter at the school.
Mr Ferreira told reporters he ran into a classroom with 14 students.
He said bullets flew through the classroom windows, hitting one student who was shot in the foot and chest.
He said a child in an adjacent classroom was shot under the arm. Both children were conscious and talking after they were shot.
Ferreira said he saw a gunman, who looked to be in his 30’s or 40’s, and was dressed in green camouflage clothing as he ran from the school after the brutal attack.
Residents in the Rancho Tehama area have been asked to stay in their homes until the area is secured and shooters are captured.