PORTER RANCH, Calif. (KABC) -- A teenager was arrested for allegedly making a criminal threat against a Porter Ranch school, police said Thursday.Los Angeles police's Major Crimes Unit was notified of the threat at Porter Ranch Community School and officers began investigating at about 4:20 p.m.The suspect was arrested based on an LAPD assessment. The teenager is being held at juvenile hall.Police are not disclosing the nature of the threat, and the identity of the suspect was not known.Porter Ranch Community School is set to open as usual Friday.