Firefighters in Bremerton, Washington are still scratching their heads after a mysterious house fire in which the source seems to have put itself out.

Investigators say a fish tank may have sparked the blaze in the home last Sunday which was vacant as the residents were on vacation. But as the flames rose, the fire cracked the tank, causing water to flood out, and douse the flames.

When the couple returned to their home, they found it intact, but filled with ashes from the fire.