Around 100 law enforcement personnel are now present at five crime scenes in the area.
Authorities have recovered a semiautomatic rifle and two handguns after the shootings in the rural subdivision described on its website as a "quiet private country community" where "the people are friendly and the pace is relaxed".
Officials said they were called around 8 a.m. Tuesday to a home near Rancho Tehama School where a man was reportedly shot. One target was an elementary school, where two children were wounded.
But police said Tuesday's incident spanned multiple shooting scenes involving multiple victims, and that three deaths, including the shooter, stemmed from the shootings.
All other student were transported to a safe location following the shooting.
The nearby Rancho Tehama Airport was placed on lockdown.
He said the gunman was a neighbor and had "been shooting a lot of bullets lately, hundreds of rounds, large magazines". "We made it aware that this guy is insane and he's been threatening us".
Some students at the school were medically evacuated; it's not clear yet how many people were injured in the shooting.
Another student in a neighboring room was also shot, Ferreira added. "They went around the community shooting at the schools!" "We offer our condolences to the families who lost loved ones and unite with all Californians in grief".