His home had 11 firearms owned by his father, though they were stored locked up.
From an article:
A 12-year-old boy faces possible felony charges after authorities say he threatened via email to carry out a mass shooting today at Twin Peaks Middle School, setting off a scramble to identify and stop him.
The boy, a seventh-grade student at the Poway school, was being evaluated Sunday night at a hospital after investigators tracked him down and served a search warrant Saturday at his family home.
Eleven guns were found there under lock and key, and the boy didn’t have access to them, the San Diego County Sheriff’s Department said.
In the email, the boy listed one of his teachers by name and 23 unidentified classmates as his targets.
He also wrote about several types of firearms and said he had 3,000 rounds of ammunition. ...
The boy sent the email to a school administrator on Friday evening, authorities said. In it, he identified a specific teacher as a target and “at least 23 children” and made references to several firearms, including a .38-caliber Smith & Wesson revolver and an M-16 rifle.
He also gave locations on campus for the shooting and wrote that it would take place today during second period, or about 9:30 a.m. ....
Sheriff’s Capt. Bill Donahue said the student was identified and authorities were at his family’s Poway home with a search warrant by 5:30 p.m. Saturday.
The boy’s father owned several guns — all of them locked up and not accessible to the teenager — including five rifles, three shotguns and three handguns, all of which were confiscated, officials said.
Donahue said the boy’s parents were shocked and cooperated fully. There was no evidence that anyone else was involved in the threat.