incredible picture. A boulder crashed into the bedroom of a utah woman in the middle of the night, while she was sleeping. She's certainly lucky to be alive this morning. And abc's nick watt has her... See More
incredible picture. A boulder crashed into the bedroom of a utah woman in the middle of the night, while she was sleeping. She's certainly lucky to be alive this morning. And abc's nick watt has her story. Reporter: There it is. 12 feet by 9 feet, by 9. Maybe 50 tons of solid rock, smashing through your bedroom wall at 3:00 a.M. Think about it. Scott's wife, wanda, was home alone, when that happened. I felt a weight of guilt of not being there. But the more I processed it, had I ben there in bed, she would have died. Reporter: Wanda survived by leaping on to scott's empty side of the bed. Fortune, scott was at their son's house that night. If he had been home, wanda would have been crushed by his side. Neighbors woke to wanda's screams, a cracked sternum and a gash on her jaw. With her jaw wired shut, I'm probably not going to get the full story. Reporter: The denhalters moved in last week. They liked the shade of that ridge. I was leery of the ridge line. A boulder could come crashing down the hill. Reporter: What dislodged the boulder is unclear. Some say they heard running water up there. Others blame the cold weather. Here's one of the neighbors. I would not live on that side of the street. Reporter: A lot of us imagine we'll die in bed one day. But not like this. A rude awakening, a bump in the night, doesn't even begin to describe the horror. For "good morning america," nick watt, abc news, los angeles.
This transcript has been automatically generated and may not be 100% accurate.