Salinas police are investigating a rash of burglaries that occurred in a 4-hour period last night. The three armed robberies took place in the city’s south and north areas between 5-to-9 p.m. The first robbery occurred at an Auto Center Circle AM-PM at 7:30, an hour later a North Sanborn Road 7-11 was hit, followed by an East Laurel Drive robbery of a Winchell’s Donuts at 9:20. Police say all the robberies appear to be related. In all cases the robber had a large black gun, and was described with the same build wearing either a black or blue ski mask. He was last seen running towards Natividad Road.