By Curtis Skinner and Peter Henderson
OAKLAND, Calif. (Reuters) - The confirmed death toll from a blaze that engulfed a converted warehouse during a dance party in Oakland, California, rose to 36 on Monday, the greatest loss of life from a U.S. fire in over a decade, as investigators sifted through charred ruins being treated as a crime scene.
Authorities said they were certain to find more bodies in the gutted building and were still trying to account for some 50 people reported missing by loved ones, although officials predicted the death tally would not climb drastically higher.
The cause of the fire, which erupted late on Friday in a sprawling two-story building leased to an artists' collective, has yet to be determined.
Officials have said arson was not immediately suspected. But Alameda County District Attorney Nancy O'Malley told an afternoon news conference that a potential criminal case could ultimately encompass charges ranging from involuntary manslaughter to murder.
One thrust of the investigation was expected to focus on possible safety violations at the site, which city officials said was already under investigation for reports of illegal construction.
Investigators from the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives identified an "area of interest" on the ground floor that was still out of reach, according to Sergeant Ray Kelly, a spokesman for the Alameda County Sheriff's Office.
He described the spot as located to the rear of the warehouse where makeshift studios and cubicles were clustered.
O'Malley said fire investigators and a task force from her office were working with recovery teams inside the wreckage to preserve any potential criminal evidence as they comb through rubble for signs of victims and clues to origins of the blaze.
Deputy Fire Chief Darren White said his crews were removing debris "bucket by bucket," but a large construction crane was also brought to the scene, requiring electricity lines in the vicinity to be shut down as a precaution for several hours.
FIRE HAZARDS
The nature of the fire has raised questions about whether building code violations might have been a factor. City officials have said the warehouse, known locally as the Ghost Ship, was under scrutiny for complaints of unpermitted interior construction. An inspector visited the property on Nov. 17.
Municipal authorities also cited reports of people living in the structure even though residential use was not permitted. A number of individuals who had been inside the warehouse described it as a potential fire trap.
The first floor of the building, which housed an artist cooperative named the Satya Yuga Collective, was a warren of partitioned studio spaces and rooms crammed with furniture, musical instruments, antiques, sculptures, wall-hangings and rugs, according to photos posted on social media before the fire and accounts of survivors and city officials.
Two recreational vehicles believed to have been used as living quarters and work space were found parked on the ground floor inside, Kelly said.
The dance party was held on the second floor, which partially collapsed when the roof gave way in the fire. Survivors said flames spread quickly and thick, black smoke filled the interior, blinding and choking occupants as they struggled to flee the cluttered space.
The building lacked sprinklers or smoke detectors, and a makeshift stairway between the first and second floors was at least partly constructed from wooden pallets, officials said. The 10,000-square-foot structure, which occupied about half a city block, had just two exterior doorways.
VICTIMS WERE YOUNG
The recovery of three more bodies from the charred ruins brought the confirmed death count to 36, a tally that made it the deadliest blaze in the United States since 100 people perished in a 2003 nightclub fire in West Warwick, Rhode Island.
"We absolutely believe that the number of fire fatalities will increase," Oakland Fire Battalion Chief Melinda Drayton told reporters before dawn. But Sheriff Gregory Ahern said later in the day he was "not anticipating any more huge numbers" of victims to be found.
About 70 percent of the site had been searched by early morning. As of Monday afternoon, 33 of the dead had been identified and authorities were notifying families, Ahern said.
Most victims were in their 20s and 30s, although some were younger, officials said. According to Kelly, the warehouse was known as a "safe-place" haven for young members of the city's lesbian, gay, bisexual and transgender community.
Three victims were from Finland, South Korea and Guatemala, Ahern said.
With many of the dead burned beyond recognition, families were asked to preserve items that might contain DNA to help identification. Kelly said some had died from smoke inhalation.
Officials were unsure how many people were present when the fire erupted. One survivor has estimated 60 to 70 were inside at the time.
The warehouse was one of many converted lofts on the east end of San Francisco Bay in Oakland's Fruitvale neighborhood, a mostly Latino district where rents are generally lower than in the rest of city.