As investigators began the painstaking search for clues to explain what caused a house to explode on Madison’s Southwest Side Wednesday afternoon, officials were not ruling out that somebody was inside the house during the blast. The house that exploded at about 2 p.m. at 7806 Stratton Way, near where High Point Road intersects with Highway PD, was deemed a total loss by Madison Fire Chief Steven Davis. “We had a pretty significant fire and a pretty significant area of debris,” he said. Officials were in contact with the owners of the house after the blast, but police and fire personnel at the scene remained in “search and rescue mode” four hours later because they were still unsure if anybody was inside during the blast, Davis said.