L.A. County sheriff's detectives arrested 21-year-old Eric Yee at his house on the 23000 block of Edenton Place at about 4:30 p.m. Monday. Several firearms were found during a search of the suspect's home.
Sheriff's officials said they received information from police in Bristol, Conn., that the suspect posted the threats on an ESPN blog.
"He was posting on a very popular Internet site," said L.A. County Sheriff's Sgt. Darren Harris. "He did not mention any schools by name. In fact, he just made some statements that he potentially intended to harm someone."
Arroyo Seco Junior High School and Santa Clarita Elementary School are within minutes of the suspect's home. Harris said they increased patrols at schools in the area due to the incident. Debbie Stutts said she took her children out of school early after hearing about the threat.
"I know there's no threat, and they're fine, I've just (had) anxiety that they're not with me," she said.
Along with guns, detectives also seized computers at the house as evidence.
The suspect was booked at the Santa Clarita Valley Sheriff's Station for making terrorist threats. His bail was set at $1 million.
