Josh Powell, the husband of a missing Utah woman, apparently intentionally blew up his home Sunday, killing himself and his two young  sons, authorities said.

Graham Fire and Rescue Chief Gary Franz told the media the fire happened shortly after after a Child Protective Services worker brought the two boys for a supervised visit. Powell has been a person of interest in the 2009 disappearance of his wife, Susan Powell. She was last seen in December 2009 at the couple's home in Utah.

In an email to his lawyer, Powell said, I'm sorry. Goodbye, before setting fire to his Graham, Wash., home, authorities said.

Pierce County sheriff's spokesman Ed Troyer said authorities believe the fire was done intentionally.

This was all on him, said Troyer. He set this up. He did it.

A medical examiner is yet to identify the bodies, but Troyer said, We believe it is the three of them.

In copies of the email obtained by the sheriff's department, Powell told his lawyer, family and friends that he couldn't live with what was going on.

A medical examiner is yet to identify the bodies, but Troyer said we believe it is the three of them.

This was something that was done deliberately and intentionally, and the plan was carried out very quickly, Troyer added.

Powell had been trying to win back custoday of the boys, but last week a Washington state judge ruled that he had to first undergo a psychosexual evaluation because of images found on a computer,  the Los Angeles Times reported.

Powell prevented the social worker from entering the home, but let the boys -- Charlie, 7, and Braden, 5, inside. The social worker shortly after called her supervisors to report the smell of gas, which was followed by the home exploding.

What happened here was a deeply wrong thing. It was an act of evil. It wasn't a tragedy, Pierce County Sheriff Paul Pastor said.

The social worker is said to be physically unharmed, but shaken up by the incident.