LONGVIEW, Wash. (AP) — Longview police say a student initially thought to have displayed a handgun in a Longview high school cafeteria was really carrying a knife.Capt. Jim Duscha says the boy flashed a large “Rambo-style” knife Wednesday morning, then snapped it back into a plastic holster. The officer tells the Daily News of Longview that other students mistook the sound for a magazine being loaded into a gun and they alerted Mark Morris High School officials. That prompted a widespread lockdown of Longview schools and Lower Columbia College.Police arrested a 15-year-old boy a short time later as he walked along a road. The officer says the knife was recovered later but he did not know where it was found. The unidentified teen was booked into a juvenile detention center for possession of a dangerous weapon, unlawful use of a weapon and obstructing a police officer. Longview Superintendent Suzanne Cusick says the school lockdowns were later lifted.