Anger was growing Saturday over the official response to a horrific inferno that levelled a Hawaiian town, killing at least 89 people in the deadliest wildfire in the United States for over 100 years.

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

Hawaiian authorities have begun a probe into the handling of the fire, with residents saying there had been no warning.

"The mountain behind us caught on fire and nobody told us jack," Vilma Reed 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 now dependent on handouts and the kindness of strangers.

"This is my home now," the 63-year-old said, gesturing to the car she has been sleeping in with her daughter, grandson and two cats.

Lahaina, a town of more than 12,000 and former home of the Hawaiian royal family, has been reduced to ruins, its lively hotels and restaurants turned to ashes.

A banyan tree at the center of the community for 150 years has been scarred by the flames, but still stands upright, its branches denuded and its sooty trunk transformed into an awkward skeleton.

- Deadliest in a century -

Governor Josh Green told reporters Saturday that the number of confirmed dead would continue to grow.

"There are 89 fatalities that have been measured," he said. "It's going to continue to rise. We want to brace people for that."

The new toll makes the blaze the deadliest in the United States since 1918, when 453 people died in Minnesota and Wisconsin, according to the non-profit research group the National Fire Protection Association.

Maui Police Chief John Pelletier said only a fraction of the disaster zone had been searched, and only two of the 89 victims have been identified because of how badly they were burned.

"The remains we're finding are from a fire that melted metal," he said. "We have to do rapid DNA to identify every one of these.

"When we pick up the remains... they fall apart."

- 'Underestimated the lethality' -

Hawaii congresswoman Jill Tokuda told CNN that officials had been taken by surprise by the tragedy.

"We underestimated the lethality, the quickness of fire," she said.

Green, the governor, defended the immediate response, saying the situation had been complicated by the presence of multiple fires and by the strength of the winds.

"Having seen that storm, we have doubts that much could have been done with a fiery fast moving fire like that," he said.

Hawaii Attorney General Anne Lopez said her office would examine "critical decision-making and standing policies leading up to, during and after the wildfires on Maui and Hawaii islands this week."

Maui suffered numerous power outages during the crisis, preventing many residents from receiving emergency alerts on their cell phones -- something Tokuda said officials should have prepared for.

No emergency sirens were sounded, and many Lahaina residents have spoken of learning about the blaze because of neighbors running down the street yelling at people to leave.

"We have got to make sure that we do better," Tokuda added.

The 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 more likely, and more deadly.

- Jail -

For many who fled the flames, the misery was compounded Saturday as they were prevented from returning to their homes.

Maui police said members of the public would not be allowed into Lahaina -- even some of those who could prove they lived there.

"If your home or former home is in the affected area, you will not be allowed to (enter) until the affected area has been declared safe," a press release said.

"Anyone entering the disaster area... is subject to a misdemeanor crime punishable by up to one year in jail and a $2,000 fine."

Some residents waited at a roadblock for hours hoping to be allowed in to comb through the ashes or look for missing pets or loved ones.

Then abruptly, the way was blocked, NBC News reported.

"How are people supposed to get there? The damn roads are closed," said Lahaina resident Daniel Rice.

"Get some authority out there. Figure it out. This is nonsense."