The house explosion that killed a father and his two children Sunday was intentional, according to police. Josh Powell, a Washington state man under investigation for the disappearance of his wife, appears to have set his house on fire after a social worker brought his two sons for a supervised visit. Powell closed and locked the door before the worker could come inside, and the house exploded. The social worker says she smelled gas. The police department said it received emails from Powell that led them to believe the explosion was intentional. Powell’s lawyer says he received an email saying, “I'm sorry, goodbye.” The parents of Powell's missing wife got custody of his children after Powell’s father, with whom he was living, was arrested on charges of voyeurism and possessing child pornography.