Oakland fire: Death toll rises to 36 and 'will increase'
Officials have said 36 people are now confirmed dead from a fire at a warehouse party in Oakland, California, and murder charges are possible.
Some 33 bodies have been identified, including victims from Finland, Korea and Guatemala.
Crews suspended body-recovery work for several hours due to fears that a damaged wall could collapse.
It is thought 50-100 people were in the venue, known as the Ghost Ship, when the fire broke out late on Friday.
Alameda County District Attorney Nancy O'Malley said on Monday that her office has has not yet determined whether a crime occurred.
But she said charges could range from murder to involuntary manslaughter.
US President Barack Obama paid tribute, saying: "Oakland is one of the most diverse and creative cities in our country, and as families and residents pull together in the wake of this awful tragedy, they will have the unwavering support of the American people."
Officials believe they have located the section of the building where the fire was started, but its cause is not yet known.
About 70% of the building has been searched already, Oakland Police tweeted on Monday morning, but investigators had not been able to access the site since late Sunday night.
The city of Oakland has been disclosing the identities of those killed, though withheld the name of the youngest, a 17-year-old.
The Ghost Ship fire's victims
Cash Askew, 22
David Clines, 35
Nick Gomez-Hall, 25
Sara Hoda, 30
Travis Hough, 35
Donna Kellogg, 32
Brandon Chase Wittenauer, 32
Riley Fritz, 29
Most of the victims were located in the centre of the warehouse structure, police said.
"We have 36 families not only grieving for their lost ones, but also they want to have answers. And we as a city collectively are working to find those answers," said Oakland police's Johnna Watson.
The blaze caused the roof to collapse on to the second floor, part of which then fell through to the ground floor.
The opening of a criminal investigation allows authorities to preserve evidence and see if there was any criminal responsibility, whether through arson or negligence.
The building was used to house artists in improvised studios but several reports say people were illegally living there too.
Neighbours had complained to the city about rubbish piling up on the street outside, and about the illegal tenants.
"That place was just a death trap,'' former resident Shelley Mack told the Associated Press. "I didn't think it was going to last this long before it went up or somebody shut it down.''
Families of loved ones were asked to gather things like toothbrushes and combs to aid with DNA identification.
Media in Oakland named Derick Ion Almena as the co-operator of the collective with his partner, Micah Allison.
A Facebook post by him lamenting the loss of his belongings but saying he was "blessed that my children and Micah were at a hotel safe and sound" drew a barrage of criticism online.