A fire in a dehumidifier caused extensive damage to the basement of a business in Janesville Saturday morning, according to a release. Janesville firefighters were called to 3506 N. Highway 51 around 10:50 a.m. for reports of heavy smoke in the basement of a business, officials said. Firefighters could see light smoke coming from the exterior door and found heavy smoke in the basement, according to the release. Crews found and put out a small fire in a dehumidifier.