LEBANON (AP) — Federal investigators at the scene of a deadly house explosion in Middle Tennessee say they have ruled out any accidental cause of the blast that killed one person. Agents with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives were in Lebanon on Tuesday trying to determine what caused the blast and where it happened in the house. Agency spokesman Michael Knight said investigators have ruled out accidental causes in Monday’s explosion such as a gas leak or electrical malfunction.