Firefighters had to let a Black Hawk County home burn all the way to its basement walls Sunday after potentially-explosive chemicals from a meth lab forced them to keep away. Authorities say 39-year-old Todd Gagnon of Cedar Falls and 35-year-old Ronald Galle of Waterloo were making meth when a kerosene lantern sparked the fire. They were not hurt and were later arrested on drug charges. The home near La Porte City was owned by Gagnon’s parents who are on vacation for the winter.