The emailed threat received March 29 warned of a hostage takeover and "bloodbath" at the school, officials said. Students were sent home while police searched the school, but nothing threatening was found.
The investigation led detectives to Kennewick, where they arrested a 19-year-old man and seized two computers as evidence, said Sgt. Cindi West.
The suspect has since been interviewed and released pending charges. His name has not been released but West said he is a former student at Kentwood.