The Spokesman-Review reports that Cheney police Sgt. Kelly Hembach says the post was quickly taken down but had been saved. The two students' parents called police.
The former student was located at a friend's house and arrested early Friday for investigation of felony harassment-threats to harm.
Hembach says the boy denied making any threats and said he was holding a BB gun.
The Cheney School District was notified.
Cheney is southwest of Spokane.