The explosion happened at a home on the 2000 block of South 232nd Street. The blast caused the home to collapse.
Neighbor Elsa Cafe was in the middle of a conversation with a friend in her living room when they looked out at this home across the street just in time to see it explode, she said.
"I told her that... 'Look at that house. That roof is nice. It looks almost done,' " Cafe said. "We look out the window. The moment we look out the window, the house exploded."
Neighbors said a man who had been working on the home for the past several weeks was seen crawling on his hands and knees out in the road after the blast.
'And he's saying 'Oh God, oh God. It hurts. Oh God, oh God, it hurts," said neighbor Tacie Marshall-Todd, who felt the explosion from her home across the street.
Firefighters are still trying to figure out what caused the explosion but said the man was doing some work with a torch on the roof of the home's carport when it happened. The blast caused the home to collapse, threw some walls against a neighbor's home and glass all over the road.
"I thought something had fallen out of the sky from the airplane as they go overhead," said Marshall-Todd. "And it has happened."
Investigators said there's not much they can do until Monday because the home is so unstable. They plan to bring in a track hoe to tear it apart, so they can hopefully figure out a cause.
No one was living inside the home when the explosion happened, firefighters said.
The victim suffered second and third degree burns to his torso. Medics took him to Harborview Medical Center in Seattle. He was listed in stable condition on Friday night and is expected to be okay, firefighters said.