California teen arrested with untraceable 'ghost gun' after threatening school shooting: police

Police in Menifee, California said they arrested a 17-year-old following social media threats he made to shoot "up a school" and "kids," finding a "ghost gun" cobbled together from parts and no serial number when they searched his home, ABC News reported.

The unnamed teenager, a student at Heritage High School, didn't name a specific school to shoot up but had also been harassing students, according to police. They don't know how he got the ghost gun, which can be acquired by minors because the building kits often don't require a background check for purchase.

He was booked into the Riverside County Juvenile Hall on charges including making criminal threats, possession of brass knuckles and possession of an unregistered firearm.

Menifee is about 75 miles east of Los Angeles, and promotes itself as a "Safe. Thriving. Premier Place to Be."