Chilling 911 tape from Josh Powell home torching

The 911 tapes have been released from the day Josh Powell set his house on fire, killing himself and his two sons.

Authorities still don't know what happened to his missing wife, Susan Powell, who's been missing since 2009, when the family lived in Utah.

In the 911 tapes, the social worker who brought the Powell boys to his home that fateful day is heard pleading for help.

"I'm on a supervised visitation for a court-ordered visit," Elizabeth Griffin-Hall is heard saying, "and something really weird has happened. I'm really shocked, and I could hear one of the kids crying, but he still wouldn't let me in."

Desperate for assistance and sensing danger, Griffin-Hall pleads with a 911 operator to send someone quickly.

"I'd like to pull out of the driveway because I smell gasoline, and he won't let me in," Griffin-Hall says.

Inside the house, Josh Powell is brutally attacking his children, while a frustrated Griffin-Hall waits helplessly for authorities to arrive.

"OK. How long will it be?" Griffin-Hall asks.

"I don't know, mam. They have to respond to emergencies, life-threatening situations first," the dispatcher replies.

"This could be life-threatening," Griffin-Hall stresses. "He went to court on Wednesday and he didn't get his kids back and this is really -- I'm afraid for their lives."

Moments later, Powell torches the home as an explosion rocks the neighborhood.

"Yes, he exploded the house!" Griffin-Hall cries out. "He exploded the house. He blew up the house and the kids!"

"The kids and the father were in the house?" the dispatcher asks.

"Yes," says Griffin-Hall. "He slammed the door in my face. So I kept knocking. I thought it was a mistake, I kept knocking, and then I called 9-1-1.

Powell's sister also calls 911 after getting an email from Josh Powell.

An emotional Alina Powell tells the operator, "He said something about he can't live without his sons. I'm not afraid of him, he'd never hurt me. I'm afraid of seeing something. I don't want to see it."

Even as she spoke, Josh Powell and his two sons had already perished in the fire.

To see Erica Hill's report and hear the 911 tape excerpts, click on the video in the player above.

A couple indentifying themselves as an aunt and uncle of Josh Powll released a statement to various media outlets, including CBS Seattle affiliate KIRO-TV, in which they blamed the legal system for the tragedy. To see the statement, click here.