An army of firefighters from 12 communities worked Tuesday night to extinguish a four-alarm fire apparently started accidentally by a cleaning crew at Buff Whelan Chevrolet in Sterling Heights, in what one official called the “biggest fire we’ve ever had.” Fire officials declared the blaze under control about 9:50 p.m., after working to put out the flames for more than two hours. The fire caused hundreds of thousands of dollars in damages to vehicles and the dealership’s service center.