A terrifying wildfire that left a historic Hawaiian town in charred ruins has killed at least 55 people, authorities said Thursday, making it one of the deadliest disasters in the US state's history.

Brushfires on the west coast of Hawaii's Maui island -- fueled by high winds from a nearby hurricane -- broke out Tuesday and rapidly engulfed the seaside town of Lahaina.

The flames moved so quickly that many were caught off-guard, trapped in the streets or jumping into the ocean in a desperate bid to escape.

"It really looks like somebody came along and just bombed the whole town. It's completely devastated," said Canadian Brandon Wilson, who had traveled to Hawaii with his wife to celebrate their 25th anniversary, but was at the airport trying to get them a flight out.

"It was really hard to see," he said, teary-eyed. "You feel so bad for people. They lost their homes, their lives, their livelihoods."

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.

"What we've seen today has been catastrophic... likely the largest natural disaster in Hawaii state history," Governor Josh Green said.

"In 1960 we had 61 fatalities when a large wave came through Big Island," he said earlier in the day, referring to a tragedy that struck a year after Hawaii became the 50th US state.

"This time, it's very likely that our death totals will significantly exceed that."

Maui County officials said just after 9:00 pm Thursday (0700 GMT Friday) that fatalities stood at 55, and firefighters were still battling the blaze in the town that served as the Hawaiian kingdom's capital in the early 19th century.

Pictures taken by an AFP photographer who flew over Lahaina showed it had been reduced to blackened, smoking ruins.

The burned skeletons of trees still stand, rising above the ashes of the buildings to which they once offered shelter.

Green said 80 percent of the town was gone.

"Buildings that we've all enjoyed and celebrated together for decades, for generations, are completely destroyed," he said.

Thousands have been left homeless and Green said a massive operation was swinging into action to find accommodation.

"We are going to need to house thousands of people," he told a press conference.

"That will mean reaching out to all of our hotels and those in the community to ask people to rent extra rooms at their property."

President Joe Biden on Thursday declared the fires a "major disaster" and unblocked federal aid for relief efforts, with rebuilding expected to take years.

- 'Bodies in the water' -

US Coast Guard commander Aja Kirksey told CNN around 100 people were believed to have jumped into the water in a desperate effort to flee the fast-moving flames as they tore through Lahaina.

Kirksey said helicopter pilots struggled to see because of dense smoke, but that a Coast Guard vessel had been able to rescue more than 50 people from the water.

"It was a really rapidly developing scene and pretty harrowing for the victims that had to jump into the water," she added.

For resident Kekoa Lansford, the horror was far from over.

"We still get dead bodies in the water floating and on the seawall," Lansford told CBS.

"We have been pulling people out... We're trying to save people's lives, and I feel like we are not getting the help we need."

Green said around 1,700 buildings were believed to have been affected by the blaze.

"With lives lost and properties decimated, we are grieving with each other during this inconsolable time," Maui Mayor Richard Bissen said.

"In the days ahead, we will be stronger as a... community," he added, "as we rebuild with resilience and aloha."

- Evacuations -

Thousands of people have already been evacuated from Maui, with 1,400 people waiting at the main airport in Kahului overnight, hoping to get out.

Maui County has asked visitors to leave "as soon as possible," and organized buses to move evacuees from shelters to the airport.

The island hosts around a third of all the visitors who holiday in the state, and their dollars are vital for the local economy.

At the airport in Kahului, Lorraina Peterson said she had been stuck for days without food or power, and was now looking at a lengthy wait for a flight.

"I don't know if we'll be able to get a hotel room, or we'll have to sleep here on the floor," she said.

With a hurricane passing to the south of Hawaii, high winds fueled flames that consumed dry vegetation.

Thomas Smith, a professor with the London School of Economics, said that while wildfires are not uncommon in Hawaii, the blazes this year "are burning a greater area than usual, and the fire behavior is extreme, with fast spread rates and large flames."

As global temperatures rise over time, heat waves are projected to become more frequent, with increased dryness due to changing rainfall patterns creating ideal conditions for bush or forest fires.