The death toll in Hawaii from the deadliest US wildfire in more than a century ticked towards 100 Sunday, fueling criticism that government inaction contributed to the heavy loss of life.

Officials say 93 people are known to have died, but warned the figure was likely to rise as recovery crews with cadaver dogs work their way through hundreds of homes and burned out vehicles in Lahaina.

The historic coastal town on the island of Maui was almost completely destroyed by the fast-moving inferno early Wednesday morning, with survivors saying there had been no warnings.

When asked Sunday why none of the island's sirens had been activated, Hawaii Senator Mazie Hirono said she would wait for the results of an investigation announced by the state's attorney general.

"I'm not going to make any excuses for this tragedy," Hirono, a Democrat, told CNN's "State of the Union."

"We are really focused, as far as I'm concerned, on the need for rescue, and, sadly, the location of more bodies."

More than 2,200 buildings were damaged or destroyed as the fire tore through Lahaina, according to official estimates, wreaking $5.5 billion in damage and leaving thousands homeless.

"The remains we're finding are from a fire that melted metal," said Maui Police Chief John Pelletier. "When we pick up the remains... they fall apart."

That was making identification difficult, he added, appealing for those with missing relatives to give DNA samples that might speed up the process.

Pelletier said cadaver dogs still had a vast area to search in the hunt for what could still be hundreds of people who are unaccounted for.

"We're going as fast as we can. But just so you know, three percent -- that's what's been searched with the dogs," he said.

- Questions over alert system -

The wildfire is the deadliest in the United States since 1918, when 453 people died in Minnesota and Wisconsin, according to nonprofit research group the National Fire Protection Association.

The death toll surpassed 2018's Camp Fire in California, which virtually wiped the small town of Paradise off the map and killed 86 people.

Questions are being asked over how prepared authorities were for the catastrophe, despite the islands' exposure to natural hazards like tsunamis, earthquakes and violent storms.

In its emergency management plan last year, the State of Hawaii described the risk wildfires posed to people as being "low."

Yet the layers of warning that are intended to buffer a citizenry if disaster strikes appear not to have operated.

Maui suffered numerous power outages during the crisis, preventing many residents from receiving emergency alerts on their cell phones.

No emergency sirens sounded, and many Lahaina residents spoke of learning about the blaze from neighbors running down the street or seeing it for themselves.

"The mountain behind us caught on fire and nobody told us jack," resident Vilma Reed, 63, told AFP.

"You know when we found that there was a fire? When it was across the street from us."

Reed, whose house was destroyed by the blaze, said she was dependent on handouts and the kindness of strangers, and was sleeping in a car with her daughter, grandson and two cats.

The New York Times reported Sunday that firefighters sent to tackle the flames found some hydrants had run dry.

"There was just no water in the hydrants," the paper quoted firefighter Keahi Ho as saying.

- Roadblocks -

The congregation of Grace Baptist Church, which was leveled in the blaze, gathered Sunday in a coffee shop in Kahului for two hours of solace.

Pastor Arza Brown led the service in his sandals, the only shoes that survived the blaze that destroyed his house.

But the trappings of ministry were far from his mind as he comforted fellow evacuees.

"That's one thing about getting together today -- just to be with each other and encourage each other," he said.

For some survivors, the difficult days after the tragedy were being worsened by what they see as official intransigence, with roadblocks preventing them from getting back to their homes.

Maui police said the public would not be allowed into Lahaina while safety assessments and searches were ongoing -- even some of those who could prove they lived there.

Maui's fires follow other extreme weather events in North America this summer, with record-breaking wildfires still burning across Canada and a major heat wave baking the US southwest.

Europe and parts of Asia have also endured soaring temperatures, with major fires and floods wreaking havoc. Scientists say human-caused global warming is exacerbating natural hazards, making them both more likely and more deadly.