OAKLAND, Calif., Dec. 4 (UPI) -- Authorities announced Sunday morning that 33 bodies have been recovered from the Oakland warehouse and arts collective fire.
The death toll on Sunday night reached 33 as fire officials contemplated ways to search more of the burned out building, including cadaver dogs and robots because the inside of the building is basically a heap of debris. With at least 30 deaths, it's the worst fire in recent California history, eclipsing the 25 who died in the 1991 Oakland Hills fire.
The fire broke out around 11:30 p.m. Friday in a warehouse known as the "Ghost Ship" used by an artist collective. They hosted the party with musical acts Friday night.
Twenty-five people originally were unaccounted for -- by people who escaped the fire or believe they knew someone who was there, Oakland Fire Chief Teresa Deloach Reed said.
Fire department officials said about 50 people were believed to be inside the building at the time of the blaze. Kelly said they mostly were in their 20s and 30s, including visitors from other countries, though some of the victim of the blaze already found have been 17 years old or potentially younger.
Alameda County Sheriff Sgt. Ray Kelly said 20 percent of the building had been searched in the past 12 hours. Kelly called the death toll an "astronomical number" but warned that officials expect the number to rise as the search continues. Officials asked the families of the missing to preserve DNA samples of loved ones to help in the ID process.
On Saturday night, nine bodies recovered were sent to the coroner's office for identification as a tractor, bulldozers and crane were being used to get into the building. Kelly said it could take at least 48 hours to determine the number of casualties because of remaining danger.
"We have to move slow and judiciously," Kelly said. "We know there are bodies in there that we cannot get to. ... We don't know how many people were inside when this happened."
Kelly said it was just a task to get in through the front door because of the debris and wreckage on the other side. With twisted wires, beams, wood and other debris, the building appears to have fallen in on itself, leading officials to discuss "bringing in cadaver dogs and robots to get into all the crevices."
"We're slowly making our way in," Kelly said, "and we have to go systematically because any misstep on the part of our people could mean they get injured or fall through a floor or have something fall on top of them."
Reed said most of the dead were found on the second floor of the building.
It took about five hours to extinguish the blaze. Reed noted the building did not appear to have sprinklers or a clear exit path. The cause of the fire is not known.
Calling it a "terrible tragedy," Mayor Libby Schaaf said she had met with a roomful of people still searching for loved ones.
"It was painful to tell them that it will take a considerable amount of time'' to determine the number of victims, Schaaf said. "Our focus right now is on the victims and their families and ensuring that we have a full accounting for everyone who was impacted by this tragedy."
People posted names of potential show attendees on the event's Facebook page. Survivors also listed their names.
Last month, authorities launched an investigation just into complaints about the safety of the structure, Oakland's Planning and Building Director Darin Ranelletti said Saturday.
Firefighters were hampered getting to the second floor.
"One of the issues was that leading up to the second floor there was only one way up and down," Reed told reporters. "It was my understanding that the stairwell was kind of makeshift, that they put it together with pallets."
Kelly said drones with thermal imaging capability went over the building to help officials find additional victims.
An electronic-music party called Golden Donna 100% Silk was to play Friday night at the warehouse.
Freelance journalist Sam Lefebvre told the building is a "sort of live/work art space with a lot of old decorations and furniture."
Bob Mulé told CNN more than 20 people lived in the warehouse as a "collective artists' community," paid rent and were all involved in the creation of the space.
Mule said he had gone upstairs to listen to some music in a "very tame setting." He went downstairs to work on a painting and he smelled smoke.
After noticing flames, Mulé went to get a fire extinguisher, which he was unable to use.
More than 40 people attended a vigil Saturday night at Chapel of the Chimes in Oakland.