Officials said they recovered a semi-automatic rifle and two handguns from the shooter.
About 100 law enforcement officials responded to "multiple scenes, I can think of at least five scenes", after the shooting, he said.
The school is now clear, and all other students have been brought to a safe location.
One student was shot at the school and taken to a hospital. Another was struck by a bullet, while in a vehicle with a woman, according to Johnston.
"We are cooperating with local law enforcement - we don't have any confirmed information at this point", but a statement from the superintendent will be forthcoming when they know more, she said. It is unknown where officers found the man.More news: N.Korean Soldier Flees Through Hail of Bullets
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At least one student was shot and injured at an elementary school after shootings occurred at seven separate scenes near the town of Red Bluff.
A reporter at Action News Now described anxious parents trying to get to their children at Rancho Tehama Elementary.
The shooting reportedly started at a home and moved to the school, authorities said.
The alleged shooter often fired multiple rounds during the early morning hours, and Flint said living near him was "hell".
"The insane thing is the neighbor has been shooting a lot of bullets lately - hundreds of rounds, large magazines", Flint said. "This guy has been insane, and he's been threatening us and everything".