Three firefighters were burned while fighting a fire at a long-vacant former gas station in Park Ridge on Wednesday afternoon. The fire was reported about 5 p.m. at the former Marathon gas station at Oakton Street and Northwest Highway. Heavy black smoke covered the immediate area while firefighters from several suburban communities worked to get the fire under control. Three firefighters were taken to area hospitals after suffering burns in the fire, said Park Ridge fire Chief Jeff Sorensen. The seriousness of their injuries was not immediately known. The three were not Park Ridge firefighters. Sorensen said the building was “loaded” with calcium peroxide, a hazardous material that can be used as a decontaminate in soil. Sorensen said the material was brought to the building the previous day.