Oakland, California (CNN) The search for answers continued Tuesday in Oakland as city, state and federal agencies sifted through wreckage in one of the city's deadliest building fires on record.

Bucket by bucket, investigators painstakingly removed debris from inside the warehouse-turned-art-space, narrowing the fire's origin to the rear of the building, Oakland Fire Deputy Director Darin White said. By Monday afternoon, about 70% of the building had been cleared.

In another area of the property, the sheriff''s coroner began autopsies on the 36 bodies so far discovered, Alameda County Sheriff Gregory J. Ahern said.

A criminal investigation team from the Alameda County District Attorney's Office is on site, working alongside law enforcement, the Oakland Fire Department and federal investigators to ascertain criminal liability, and, if so, who could be responsible, District Attorney Nancy O'Malley said.

"It is not clear right now and is too early to speculate," she said of the circumstances of the fire that broke out late Friday. "We will leave no stone unturned."

Meanwhile, questions remain about leaseholder Derick Ion Almena, the man behind the arts collective known as the Ghost Ship , and what, if anything, could have been done to prevent the tragedy. Almena, who is believed to have been away from the site when the fire broke out, has not responded to CNN's requests for comment, but spoke to CNN affiliate KGO

"They're my children. They're my friends, they're my family, they're my loves, they're my future," Almena told the station, referring to the Ghost Ship residents. "What else do I have to say?"

Death toll keeps climbing

In the wake of the tragedy, a fence and sidewalk near the site became a memorial, with loved ones and others leaving flowers, candles, photographs and messages.

At least 36 people are confirmed dead, including teenagers, a deputy's son, and three people from outside the US, in the blaze, which gutted the converted warehouse during an electronic dance party Friday night. Twenty-two victims have been positively identified and their families have been notified. An additional 10 victims have been tentatively identified and three victims need scientific identification, the city said in a statement.

Most of the bodies were found in the center of the building, Oakland Fire Battalion Chief Melinda Drayton said.

The fire spread so quickly that resident Jose Avalos had no time to help, he told CNN. He was in his loft when he heard someone call for an extinguisher. Before he could get down to offer support, he heard someone say, "Fire! Everyone get out!"

He grabbed his dogs and rushed to the front door where he fell into others trying to escape, he said.

"By the time I was through the front doors, I could just see the flames coming and then they just engulfed the front archway of my studio," he said. "I looked back and I just saw smoke everywhere. I couldn't really see anything. Got out of the building and I just saw smoke and then flames coming out the doors and the windows."

One of deadliest fires ever in Oakland

It could take weeks to identify victims through DNA and dental records, Alameda County Sheriff's Office Sgt. Ray Kelly said. Officials have asked victims' families to preserve their loved ones' personal belongings, including hairbrushes and toothbrushes, that could contain DNA samples. Kelly added that officials were also working with the transgender community to identify some of the victims.

Drayton, a 19-year veteran, called it one of the deadliest fires in the city's history, including a 1991 fire in Oakland Hills that killed 25 people.

Southern California artist Anneke Hiatt, who has been monitoring the situation because she had friends there, said she is starting to lose hope.

"It just doesn't seem that that's a fire that's survivable, so the reality, I think for a lot of us, is beginning to set in," she said.

'I had to let him go'

Photos: Oakland warehouse party fire A fire breaks out Friday night, December 2, during a party at a two-story warehouse and artists' studio in Oakland, California. Initial reports indicate dozens of people were in the building when the deadly blaze started, the Oakland fire chief says. Hide Caption 1 of 7 Photos: Oakland warehouse party fire The scene as firefighters battle the blaze from video footage by @Oaklandfirelive early Saturday, December 3. Hide Caption 2 of 7 Photos: Oakland warehouse party fire Firefighters begin to assess the scene of the warehouse fire on December 3. Hide Caption 3 of 7 Photos: Oakland warehouse party fire Firefighters have not been able to search the entire building, the fire chief says. Hide Caption 4 of 7 Photos: Oakland warehouse party fire Crew will remove debris and make sure the warehouse is safe for searching. Hide Caption 5 of 7 Photos: Oakland warehouse party fire Firefighters clear an entry to the smoldering warehouse. Hide Caption 6 of 7 Photos: Oakland warehouse party fire Officials will begin investigating to determine the cause of the fire. The Alameda County Sheriff's Coroner's Bureau and the Arson Task Force were called to the scene. Hide Caption 7 of 7

For filmmaker and photographer Bob Mulé, the warehouse was both his home and his community. The 27-year-old stopped to listen to some music Friday night before heading downstairs to work on a painting. He smelled smoke from his studio.

As Mulé rushed to save his camera and laptop, he spotted a heavy-set artist who called out for help.

"I broke my ankle. I need you to pull me out," a distraught Mulé recalled the artist saying. "The fire was just getting too hot and the smoke was just getting too bad and I had to leave him there."

A haven for artists

The interior of The Ghost Ship, the warehouse that caught fire on Friday, December 2.

To the artists who lived and worked there, the Ghost Ship was a coveted haven in the Bay Area's gentrifying landscape of skyrocketing rents and disappearing artist spaces. Residents estimate 20 to 25 artists lived there.

Photos posted online show an interior containing drums, keyboards, guitars, clocks, ornate beds, plush sofas, mirrored dressers, tables, benches and artifacts. Exotic lamps hung from the ceiling, and paintings adorned the walls.

"It was not a bunch of irresponsible people looking for a drug thrill," Swan Vega, a 33-year-old resident, told CNN. "It was a known community house, a place for the creative class to support each other, gain momentum, hash out projects, and just be joyous. And this is the most tragic outcome.

Darin Ranelletti, Oakland's interim director of planning and building, said the city approved permits for the building to be used only as a warehouse, not for residences. City officials also had not signed off on a special permit for the event, Ranelletti said.

In addition, firefighters found no evidence of sprinklers in the warehouse.

Vega, who said "nobody should've been living there," called for more affording housing for artists in the Bay Area.

"We need housing," she said. "We need help."

Past concerns

Last month, the warehouse's owners had received notification of city code violations for hazardous trash and debris, property records show.

Former California State Chief Fire Marshal James McMullen said it was his understanding that the owner of the space had been approached about illegal occupancy and trash and debris strewn "around in the way of forming a fire hazard."

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Shelley Mack, a jewelry maker who lived at the Ghost Ship until February 2015, said she paid $700 to move in and another $700 for improvements that never came. The sole bathroom for residents was in bad repair, a transformer blew a couple of weeks after she moved in and fires were sparked by faulty electrical cords, she said. The space had intermittent power and heat when she lived there, she said.

"Not long after I moved in, I found out we had to hide our things when the owner came by because it's not slated as a live/work place and we all lived there," she said. "I expected it to be shut down a long time ago."

Mack claimed police were well aware people were living in the warehouse because they were called there weekly. She called police herself three times in one week, and other government agencies, including Child Protective Services, paid visits to the warehouse, she said.

City Councilman Noel Gallo lives a block from the Ghost Ship and told CNN he was aware people were living there. After hearing Mack's allegations, he said, "It's really inexcusable in terms of our response."

Gallo knew the owner and the manager of the space and said "we've had a good number of conversations regarding the upkeep of the property on the street level/sidewalk level, as well as on the inside."

Drayton, the fire battalion chief, told reporters Monday that if Oakland police had been called to the warehouse, they might have captured footage that could be useful to the investigation.

"We're looking at everything from our body-worn camera footage, how many calls we at the Oakland Police Department have gone to, what types of calls, documentation when working with our planning and building department," she said. "We have a lot of moving parts."

CNN has reached out to the property owners for comment.