The probable cause of Orinda, was hot coals from a Weber barbecue grill on the back wooden deck left from the night before, the fire chief reported.
"The cause was inconclusive," wrote Moraga-Orinda Fire District Chief Randy Bradley in an email. "We are confident the fire started on the exterior rear wooden deck and we ruled out all other likely ignition sources."
The Otsmaa family was out of town traveling at the time, and house sitters were at the ridgetop house. There were no injuries reported.
Silvi Otsmaa said she suspects a raccoon may have tipped over the small grill, spilling coals on the deck.
Watch for a feature later on Lamorinda Patch about the Otsmaa family as they rebuild their lives and express thanks for the community and neighborhood support they have received.