How did the Maui fire start? What we know about the cause of the Lahaina blaze (2023)

Deadly wildfires in Hawaii, which killed scores of peopleand forced thousands to evacuate, were fueled by a mix of land and atmospheric conditions that can create "fire weather." A massive blaze destroyed much of the historic town of Lahaina, on Maui, and authorities said Monday the death toll was nearing 100.

Hawaii Gov. Josh Green said Sunday there is "very little left" of Lahaina, where more than 2,700 structures have been destroyed in what is now the deadliest U.S. wildfire in more than a century. Green said he expects the death toll to keep climbing.

"There are more fatalities that will come," Green told CBS News. "The fire was so hot that what we find is the tragic finding that you would imagine, as though a fire has come through and it's hard to recognize anybody."

• How to help those affected by the Maui wildfires

What caused the Maui fire?

Much of Hawaii was under a red flag warning for fire risk when the wildfires broke out, but the exact cause of the blaze is still unknown.

"We don't know what actually ignited the fires, but we were made aware in advance by the National Weather Service that we were in a red flag situation — so that's dry conditions for a long time, so the fuel, the trees and everything, was dry," Maj. Gen. Kenneth Hara, commander general of the Hawaii Army National Guard, said at a briefing Wednesday. That, along with low humidity and high winds, "set the conditions for the wildfires," he said.

"The winds were just getting out of control. Power lines were down everywhere.," Maui resident J.D. Hessemer, who owned a business in Lahaina, later told "CBS Mornings." "We just decided it was not safe to stay around for the day."

Echoing wildfire experts, Gov. Green said Friday that he believes a confluence of weather conditions contributed to the ignition and spread of the blazes.

"It is a product, in my estimation, of certainly global warming combined with drought, combined with a super storm, where we had a hurricane offshore several hundred miles, still generating large winds," Green told CNN.

The powerful winds fanning the flames were generated by Hurricane Dora, a storm that was moving across the Pacific Ocean hundreds of miles south of the Hawaiian islands, the National Weather Service said.

The hurricane, classified as a Category 4 by the Central Pacific Hurricane Center on Wednesday morning, contributed to heavy wind gusts above 60 miles per hour that tore through Maui, knocking out power lines and damaging homes.

Claims surfaced over the weekend that suggested the power company Hawaiian Electric, which operates Maui Electric and services95% of the state overall, did not implement precautionary safety measures included in an emergency plan to reduce wildfire risks ahead of the storm. Citing documents, a Washington Post report published Saturday noted that the provider did not shut off electricity to areas where strong winds were expected and could spark flames.

A spokesperson for Maui Electric told CBS News in a statement that some steps were taken to mitigate the possibility of fires sparking before hurricane winds arrived.

"Hawaiian Electric has a robust wildfire mitigation and grid resiliency program that includes vegetation management, grid hardening investments and regular inspection of our assets," the statement read. "The company has protocols that may be used when high winds are expected, including not enabling the automatic reclosure of circuits that may open during a weather event. This was done before the onset of high winds. ... At this early stage, no cause for the fire has been determined."

National Guard helicopters activated as part of the state's emergency response to the wildfires were grounded as the wind gusts picked up on Tuesday evening, Aug. 8.

Acting Hawaii Gov. Sylvia Luke issued an emergencyproclamationauthorizing the deployment of National Guard troops, and extended the state of emergency. President Biden approved a federal disaster declaration on Thursday.

The National Weather Service noted in atweet before the fires started that significant differences in atmospheric pressure between the hurricane and the air north of Hawaii formed a pressure gradient over the islands which, when combined with dry conditions, posed a serious threat of fires as well as damaging winds.

"While Hurricane Dora passes well south with no direct impacts here, the strong pressure gradient between it & the high pressure to the north creates a threat of damaging winds & fire weather (due to ongoing dry conditions) from early Mon to Wed," the agency said at the time.

Meanwhile, Hawaii Emergency Management Agency spokesperson Adam Weintraub told The Associated Press on Thursday that the department's records don't show that Maui's warning sirens were triggered on Tuesday. Instead, the county used emergency alerts sent to mobile phones, televisions and radio stations, Weintraub said.

Rep. Jill Tokuda of Hawaii, who represents the area in Congress, alsosaidthat the state's warning sirens "likely did not go off." She told CBS News' "Face the Nation"that warnings typically sent to mobile phones could have been affected by mass power outages, preventing people from accessing useful information and guidance on how they should proceed.

Making matters worse, residents said the fire hydrants ran out of water, hindering firefighters' ability to contain the blazes. FEMA officials confirmed there was an issue that affected the hydrants' water supply.

Hawaii Attorney General Anne Lopez announced Friday that her agency would conduct a "comprehensive review of critical decision-making and standing policies leading up to, during, and after the wildfires."

How do wildfires usually start?

Almost 85% of wildfires in the United States are caused by humans, according to theNational Park Service. Fires that are sparked this way can result accidentally from leaving campfires unattended, burning debris, using various kinds of equipment and discarding cigarettes improperly. Intentional acts of arson are another source of human-caused wildfires, the agency says.

Lightning and volcanic activity are two natural causes of wildfires, although officials note that lightning strikes are a much more common catalyst.

Certain weather can ignite and help spread fires, with strong winds, low relative humidity, unstable atmospheric conditions and thunderstorms contributing to what meteorologists call "fire weather," said Nick Nauslar, a meteorologist and former weather forecaster at the National Oceanic and Atmospheric Administration's Storm Prediction Center, in a 2018 FAQ published by the agency.

Most often, lightning strikes a tree and ignites a fire, but strong winds can also spark power lines that go on to ignite wildfires when there is dry brush or grass in the area, according to NOAA, which says wildfires can spread quickly in hot, dry and windy conditions — especially when those conditions happen simultaneously. The wildfire season has been severe in Canada and across North America this year, as warm and dry conditions persist while various sections of the continent experience record heat and drought as a result of climate change.

Maui Fire officials had warned in analertissued Tuesday, Aug. 8, that "erratic wind, challenging terrain, steep slopes and dropping humidity, the direction and the location of the fire conditions make it difficult to predict path and speed of a wildfire." It noted that "fires can start at a far distance from their source" when wind pushes embers upward and sparks are ignited downwind.

"The fire can be a mile or more from your house, but in a minute or two, it can be at your house," said Fire Assistant Chief Jeff Giesea in a statement included in the alert. "Burning airborne materials can light fires a great distance away from the main body of fire."

Where are the fires in Maui?

Firefighters were continuing to fight flames in Lahaina and Upcountry Maui, including ongoing fires and flare-ups, theCounty of Maui said Monday.

Officials saidthe Lahaina fire was 85% contained and the Upcountry/Kula fire was 60% contained, while the Pulehu/Kihei fire had been 100% contained.

The county noted that even when a fire is 100% contained, that does not mean it has been extinguished but that firefighters had it "fully surrounded by a perimeter."

What about Hawaii's warning sirens?

Hawaii has a statewide outdoorwarning siren system, which can be used to notify residents ahead of natural disasters or human-caused events, including tsunamis, hurricanes, dam breaches, flooding, wildfires, volcanic eruptions, terrorist threats and hazardous material incidents, according to the Hawaii Emergency Management Agency.

But U.S. Rep. Jill Tokuda, whose district includes Maui, said Sunday on "Face the Nation"that the warning sirens "likely did not go off." Maui's fire chief later confirmed to CBS News' Jonathan Vigliotti that the sirens did not go off.

"Everybody who has ever lived in Hawaii knows the warning sirens. It goes off once a month, every month, at 12 noon and it blares. And if it doesn't, it gets fixed because that is our first line of defense," Tokuda said.

"Sadly, tragically, in this situation, those sirens likely did not go off," said the congresswoman. She also suggested that warning signals typically sent to mobile phones could have been affected by the widespread power outages reported on Maui at the time. Those outages likely prevented many people from accessing key information.

"The reality is, with those warning signs, it tells all of us to turn on the television or look on our phones or turn on the radio," she said. "With how fast this burn was ... if you turned on your phone, if you turned on a radio, if you even could ... you would not know what the crisis was. You might think it's a tsunami, by the way, which is our first instinct. You would run towards land, which in this case would be towards fire."

As the fires raged, crews rescued 17 people who jumped into the Lahaina harbor in an effort to escape the flames, the U.S. Coast Guard said. On Front Street, a popular tourist destination, business owner Alan Dickar described seeing buildings on both sides of the street "engulfed" in flames. "There were no fire trucks at that point; I think the fire department was overwhelmed," Dickar told CBS Honolulu affiliateKGMB-TV.

Speaking later to CBS News' Patrick Torphy, he added: "Maui can't handle this. ... A lot of people just lost their jobs because a lot of businesses burned. A lot of people lost their homes. ... This is going to be devastating for Maui."

In:
• Hawaii Wildfires
• Fire