The explosion occurred Thursday afternoon. Thornton Fire Chief John Staley said Friday investigators had not yet determined the cause -- although they were considering gas -- and the body might remain in place until they finish their work at the scene.
"Now the laborious process of determining the cause starts and that's key to the investigation. That's why we haven't moved the body," Staley said.
The identity of the victim, described as a man in his 20s, had not been released. The owners of the home were not there at the time of the explosion.
Sarah Smith told KCNC-TV in Denver that her two Chihuahuas were missing. She said she thought her husband was kidding when he told her about the blast.
"My neighbor called my husband and said that our house blew up and I told him he was lying," she said. "I just never thought it would happen to me."
The blast was powerful enough to send debris flying two blocks away.