A warehouse fire in California that killed 36 people does not appear to have been started intentionally and may have been caused by a refrigerator or other electrical appliance, investigators have said.
Details about a possible cause emerged as fire crews nearly completed their search for bodies in the most lethal building fire in the US in more than a decade. The death toll remained at 36 and is not expected to go higher.
Tearful family members visited the scene in Oakland and exchanged hugs hours after the founder of the arts collective that used the warehouse stood near the gutted building and said he was "incredibly sorry".
"Everything that I did was to make this a stronger and more beautiful community and to bring people together," Derick Ion Almena said.
He said he was at the site to put his face and his body in front of the scene, but he deflected blame for the blaze, saying he signed a lease for the building that "was to city standards, supposedly".
The fire broke out during a dance party on Friday night in the cluttered warehouse. It had been converted to artists' studios and illegal living spaces, and former residents said it was a death trap of piled wood, furniture, snaking electrical cords and only two exits.
A fridge was a potential source of the fire, but it was too soon to say for sure, said Jill Snyder, special agent in charge of the San Francisco office of the Bureau of Alcohol, Tobacco, Firearms and Explosives.
She said investigators are looking at "anything electrical" on the first floor of the warehouse near the origin of the blaze.
"We have no indication that this was intentionally set," she said.
Mr Almena told San Jose television station KNTV that he did not attend the event on Friday night and that he and his wife had decided to stay at a hotel because he was exhausted.
City and state officials fielded years of complaints about dangerous conditions, drugs, neglected children, rubbish, thefts and squabbles at the warehouse, raising questions about why it was not shut down. The district attorney warned of possible murder charges as she determines whether there were any crimes linked to the blaze.
Crews have searched at least 90% of the building known as the Ghost Ship and fire officials started knocking down parts of the building they said were structurally unsound.
Alameda County Sheriff's Deputy Tya Modeste said of the 36 victims found, 26 families have been notified. Another nine bodies have been "tentatively identified", she said. Officials are still lacking any type of identity for one individual.