Officials said 56-year-old Glenn Litton shot two kindergartners, identified as 6-year-old Roman Mendez, and 5-year-old Elias Wolford. Both are still in the hospital in critical and stable condition.
"It's very likely they're going to have to have a number of surgeries going forward," said Honea. "But the fact that they are currently still with us is a miracle and something we should all be thankful for."
Not only did Litton have a lengthy criminal history, but he was released from jail in San Bernardino County less than two weeks before the shooting.
"Several (of his) convictions to various crimes include theft, fraud, forgery in the 1990's and early 2000's," said Butte County Sheriff Kory Honea during a news conference Thursday.
Litton was convicted on charges related to fraud and identity theft in 2003 and was sentenced to eight years in state prison.
But Butte County District Attorney Mike Ramsey said law enforcement was also concerned about items discovered during a search of his property during that investigation, including things Litton was apparently searching for by using his computer.
"(He was) looking for guns and looking for explosives; notes in the computer itself were fairly significant in terms of planning of some sort of mass incident involving explosives," said Ramsey.
Litton was later convicted on federal identity theft charges in August 2015 and again in April 2016. At some point, Litton came to Southern California, where he was suspected of check fraud in April 2020.
Redlands Police say Litton wrote a fraudulent check to himself in the amount of $3,850 and cashed the check at California Check Cashing at 1615 W. Redlands Blvd.
When the check bounced, it was reported to the Redlands Police Department, which investigated the case and turned it over to the San Bernardino County district attorney's office.
Burglary charges were filed, and an arrest warrant was issued for Litton. He was finally arrested by South San Francisco police in November 2020 and extradited to San Bernardino County.
Despite numerous convictions, officials said Litton had no history of violent crime. He made his first court appearance on the burglary charges in San Bernardino on Nov. 21.
"He had his first court appearance, pleaded not guilty, and was released on his own recognizance," said Honea. "He was then picked up by a family member and brought back to Sacramento."
When deputies responded to reports of an active shooter at Feather River Adventist School in Oroville on Wednesday, they discovered Litton dead from an apparent self-inflicted gunshot.
Litton was a convicted felon and therefore could not legally possess a firearm.
He was mentally ill and believed by targeting children he was carrying out "counter-measures" in response to America's involvement in Middle East violence.
"This individual did have some significant mental health issues," said Honea.
Law enforcement officials have documented Litton's history of mental illness back to when he was a teenager, though Honea said investigators have not found a concrete diagnosis.
Litton used a "ruse" of pretending to enroll a fictitious grandson to gain entry to the Feather River School of Seventh-Day Adventists in Oroville, Honea said.
Honea said the man is believed to have targeted the Feather River School in Wednesday's attack, though it's unclear why. Litton had attended a school of Seventh-Day Adventists in another town as a child, the sheriff said, and he possibly had a relative who attended Feather River as a young child.
But in Litton's writings, the sheriff said, the suspect wrote about taking "counter-measures" against the school in response to America's involvement in violence in the Middle East.
"That's a motivation that was in his mind. How it was that he conflated what's going on in Palestine and Yemen with the Seventh-Day Adventist Church, I can't speculate. I'm not sure that we'll ever know that," Honea said.
He said Litton had similarly scheduled an appointment at another Seventh-Day Adventist school, set for Thursday.
The Seventh-Day Adventist Church is a Christian denomination in which members consider the Bible their only creed and believe that the second coming of Christ is near. The shooting occurred shortly after 1 p.m. Wednesday at the private K-8 school with fewer than three dozen students in Oroville, on the edge of the tiny community of Palermo, about 65 miles (105 kilometers) north of Sacramento.
A candlelight vigil is planned for Friday.
The Associated Press contributed to this report.