Police: 12-Year-Old Planned School Shooting

A California middle school student who sent an email to a school administrator detailing plans to shoot 23 classmates and a teacher has been arrested, the San Diego Sheriff's Department said.

The threatening email, which mentioned "numerous firearms" and 3,000 rounds of ammunition, had been sent to a Twin Peaks Middle School administrator on the evening of Feb. 8, authorities said. According to the email, the mass shooting would take place at the school on Monday, Feb. 11.

Steven Seagal Training Sheriff Joe's Volunteer Posse on School Security

The Poway Sheriff's Station learned of the email on Saturday and worked with a taskforce consisting of federal, state and local authorities, who traced it to a 12-year-old student at the school.

Authorities served a search warrant on the student's home Saturday evening and seized several computers, rifles and handguns, according to the San Diego Sheriff's Department.

The student, whose name and gender have not been released, was taken to a local hospital for treatment and evaluation, authorities said.

The San Diego Sheriff's Department said it believes this is an isolated incident and that there is no evidence to suggest anyone else was involved.

The case will be submitted to the San Diego District Attorney's Office for review.

More ABC News