Police search for weaponWATERLOO (AP) — Police searched theWapsipinicon River looking for the gun that killed a Target store worker.Waterloo police and Buchanan County Sheriff’s officials resumed their search Thursday after spending five hours looking for a gun Wednesday.“We’re looking very hard; it’s a major operation, Waterloo Police Lt. Bob Greenlee said.Gary Mast, 43, of Evansdale, died shortly after he was shot once in the chest at about 9:40 p.m. Nov. 7. Mast was a part-time cart attendant at the Waterloo Target store. A store security guard was wounded.Mast’s death certificate says the gun that killed him was a .25 caliber. Police are still looking for a 43-year-old Waterloo man in connection with the shooting.Police believe the gun was dumped near an area of the river near Independence known as Willow Beach sometime after the shooting. A person led officials to the site Wednesday morning, according to reports.Lab officers and detectives from the Waterloo Police Department and 12 divers from the Buchanan County Search and Recovery team covered the river area Wednesday.They searched a 60-foot wide stretch of the river, Greenlee said.