Published: Sep 26, 2011 7:20 PM EDT

SEATTLE (AP) - The Seattle Fire Department says a natural gas leak caused an explosion and fire at a north Seattle home.
    
Spokesman Kyle Moore says a couple who lived in the house thought they smelled gas Sunday night but weren't sure so they didn't report it. He says when they woke up Monday morning they smelled gas and started turning things on, then heard the explosion.
    
Moore says fumes apparently were sparked by an appliance.
    
The couple - in their 50s -both suffered second-degree burns and are at Harborview Medical Center. The woman has life threatening injuries. The man in serious condition and was able to talk to investigators.

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