OAKLAND (CBS SF) — The city of Oakland started investigating nearly three weeks ago whether people were illegally living in a warehouse destroyed by a fire late Friday night, a city official said Saturday.

At least nine people died in the blaze and another 25 remained missing.

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The building known as the Oakland Ghost Ship was the Satya Yuga Collective–Live/Work Spaces for Artists.

Darin Ranelletti, of the City of Oakland Planning Department, said the city had received reports of people living illegally in the building, which was only permitted as a warehouse.

Oakland’s Mayor Libby Schaaf confirmed that at a press conference on Saturday.

“This morning a terrible tragedy took place in a space, in a building that is permitted as a warehouse,” she said.

“The whole building was divided up into small areas, that were basically work areas for artists,” added Oakland’s Deputy Fire Chief Mark Hoffmann. “It ranged from people to doing wood working to people doing sculpting to people doing kinetic art, so it was just a labyrinth of little areas.”

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Official had opened an investigation on Nov. 13. He says an investigator went to the premises on Nov. 17 but could not gain access to the inside of the building,

Ranelletti said they had not yet confirmed people were living inside. Photos posted online of the warehouse – called the “Oakland Ghost Ship” – showed pictures of a bohemian, loft-like interior made of wood and cluttered with beds, rugs, old sofas, pianos, paintings, turntables, statues and other items.

Neighbors had complained of trash piling up outside the property and concerns the garbage posed a danger, according to the city’s Planning and Building Department website.

City records show complaints were made as recently as mid-November about the site.

A notice of violation was given on Nov. 13 about “a ton of garbage piling up on the property,” with “the main building remodel (sic) for residential,” city records show.

Ranelletti said the building was only legally permitted for use as a warehouse and that Friday’s party and concert headlined by Golden Donna was not permitted by the city.

The concert happened on the second floor of the building, which according to members of the Satya Yuga Collective, was always under construction.

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The East Bay Times reported the building was owned by Chor N. Ng of Oakland, according to property records. He bought the warehouse in 1997. Ng owns other properties in Oakland.