A fire at a cardboard manufacturing plant smoldered for hours Sunday afternoon as firefighters from Cedar Rapids and surrounding towns worked to clear the scene. The Cedar Rapids Fire Department said crews responded around 12:30 p.m. to a report of smoke inside a paper milling station at International Paper, 4600 C St. SW. When firefighters arrived, they worked with plant personnel and found the source of the fire among machinery inside the building, officials said. As the firefighters worked to establish a water supply and set up the aerial truck, they requested mutual aid from fire departments in Ely and Swisher. According to a Cedar Rapids Fire Department news release, firefighters were able to quickly control the “main body” of the blaze.