Police have arrested a 13-year-old boy in Washington on charges of causing a threat and unlawful possession of a firearm

This image provided by Pierce County Sheriff's Office on Tuesday, Sept. 9, 2025 shows weapons seized from the home of a 13-year-old boy in Pierce County, Wa., who authorities said had appeared to idolize school shooters. (Pierce County Sheriff's Office via AP)

TACOMA, Wash. (AP) — A 13-year-old boy described by police as obsessed with school shooters was arrested on multiple firearms possession charges and causing a threat after they say they found social media posts about intentions to kill and seized 23 guns and ammunition from his home.

The boy pleaded not guilty to a total of five charges, four of them felonies, in juvenile court on Monday. He was arrested over the weekend in Washington's Pierce County.

The boy's name has not been released. It was not immediately known if he had a lawyer. Juvenile court records are generally confidential.

Firearms were mounted on walls and handguns were found unsecured throughout the home, sheriff's Deputy Carly Cappetto said in a news release Monday.

“Several pieces of evidence from the suspect’s bedroom indicated he was obsessed with past school shooters and imitated similar behaviors with photos and inscriptions throughout his room,” she said. Loaded magazines with school shooter writings on them were removed.

“It appeared the suspect had everything ready to go to commit a mass shooting type of incident. It is unknown who or what the intended target was going to be, but it’s clear it was a matter of time before a tragic incident occurred,” Cappetto said.

The boy's parents said their son had no intention of harming anyone. His mother, who attended the court hearing, suggested in an interview afterward that the social media posts were an attempt to “be cool” among peers, KOMO-TV reported.

Cappetto said the boy was last enrolled in the Franklin Pierce School District in 2021. He was currently unenrolled and was not currently an active student in any school district.

This image provided by Pierce County Sheriff's Office on Tuesday, Sept. 9, 2025 shows containers with weapons seized from the home of a 13-year-old boy in Pierce County, Wa., who authorities said had appeared to idolize school shooters. (Pierce County Sheriff's Office via AP)

This image provided by Pierce County Sheriff's Office on Tuesday, Sept. 9, 2025 shows weapons seized from the home of a 13-year-old boy in Pierce County, Wa., who authorities said had appeared to idolize school shooters. (Pierce County Sheriff's Office via AP)