Only three hours before she found herself huddled in the Pacific Ocean, a barrage of embers and ash hurtling above her, Chelsea Denton Fuqua was lounging in bed with a fan, a pristine blue sky outside the window of her home that lies half a mile from the Lahaina waterfront on the Hawaiian island of Maui.

It was moments later when she caught a glimpse of smoke in the distance. At first it was a wisp, but within minutes it had grown thicker, rippling down the hillside on violent winds.

Ms. Denton Fuqua, 32, and her husband were worried. They had received no text alerts, no sirens, no evacuation orders — no sign for her and her neighbors, she said, that Lahaina, a community of 13,000 that was once the capital of the Hawaiian kingdom, was on the cusp of incineration.

But they knew what could happen in a wildfire. They grabbed a few essentials and prepared to leave in their cars. “People were just like, ‘Oh, are you heading out?’ Ms. Denton Fuqua recalled. “‘All right, be safe.’”

Nearly a week has passed since the inferno that swept West Maui last Tuesday. At least 99 people are confirmed dead, with the toll expected to rise substantially. Thousands of structures, mostly homes, have been reduced to rubble. Husks of incinerated cars line Lahaina’s historic Front Street, while nearby search crews make their way painstakingly from house to house, looking for human remains.

The fire’s swift rampage and stunning death and destruction are already raising questions about whether there should have been more aggressive management of electrical power as high winds buffeted the island, earlier warnings for residents in the fire’s path and better management of traffic to avert the paralyzing gridlock that funneled many people into a death trap.

Interviews and video evidence reviewed by The New York Times show that the brush fire that wound up wiping out Lahaina ignited under a snapped power line a full nine hours before it roared through town — flaring up in the afternoon after firefighters had declared it contained.

Yet in dozens of interviews with people who survived, residents in neighborhood after neighborhood said they had received no warnings before the fire came rushing toward their homes. They told stories of people scrambling to escape along the waterfront and driving past others who were cluelessly frolicking on the beaches. Some stood outside their houses, marveling at what was unfolding, still sipping cocktails. Tourists who got the word packed up and fled their hotels, while others were rolling in with their luggage.

“Nobody saw this coming,” said Mark Stefl, a tile setter. He said his first clue he might be in danger was when his wife spotted flames 500 yards from their house.

As the fire spread further into town, the problems multiplied: Hydrants ran dry as the community’s water system collapsed, according to firefighters. Powerful sirens, tested every month in preparation for such an emergency, never sounded. Lahaina’s 911 system went down.

Many of those who evacuated said they were corralled by road closures and downed power lines into traffic jams that left some people to burn alive in their cars and forced others to flee into the Pacific. Videos shared with The Times and posted on social media show cars on Front Street crawling in bumper-to-bumper traffic as smoke, embers and debris billow around them.

Government officials have blamed wind gusts that in some cases exceeded 80 miles per hour for fueling the ferocity of the blaze, combined with warming temperatures and drought that left the island’s vast grasslands and brush tinder dry.

The prospect of a destructive wildfire has been a growing concern across West Maui for years, as drought has worsened, invasive plants have created huge swaths of highly flammable grasslands, and worsening storms have spawned winds that can fuel fires. All those perils came sharply into focus in the days before Maui’s fire last week, when a hurricane building to the south, with significant winds forecast, created the very conditions that scientists had long warned could be a deadly combination.

Gov. Josh Green of Hawaii has said repeatedly since the fire that climate change is “the ultimate reason that so many people perished.” He has asked the attorney general to conduct a comprehensive review.

“Over time,” he promised, “we’ll be able to figure out if we could have better protected people.”

It was shortly after sunrise on Aug. 8 and wind was already blustering down Lahaina’s west-facing slope when Shane Treu clambered onto his roof near Lahainaluna Road to repair some damage. Pieces of roofing and heavy panels for a solar water heater had been blown off and were landing on his fence.

That’s when he heard a sound from a nearby power line.

“The wind is still blowing super strong and I hear a pop,” Mr. Treu recounted. “I look and the line is just arcing, laying on the ground and sparking.” The power line, landing in dry grass, was “like a fuse,” he said. It blackened the ground at the base of a power pole and began to ignite nearby yards.

It was precisely the location where the brush fire that would eventually engulf much of Lahaina was initially reported, at 6:37 a.m., a Times analysis of video and satellite imagery shows.

Mr. Treu began filming with his phone, panning across three power lines on the ground. One could be seen dangling in charred, smoking grass. “That’s the power line that started it,” he said on the video. In an interview, Mr. Treu said he called 911 as the fire grew, across the street from his house. It took six minutes for the police to arrive, he said, and another six for the firefighters; a water tanker and two front-end loaders arrived to create a fire break.

County officials reported that the fire was “100% contained” by 9 a.m.

Mr. Treu said he resumed his repairs and then had his son drive him to one of his two jobs. In the back of his mind, he found himself wondering whether the fire might flare up again.

It did.

Maui officials put out a news release that said there had been an “apparent flare-up” of the Lahaina fire, and that the Lahaina Bypass — the road constructed in 2013 after residents complained for years that they might be trapped on the town’s single in-and-out road — was closed at around 3:30 p.m.

Mr. Stefl and his wife, Michele Numbers-Stefl, already spotted a fire an hour earlier about 500 yards from their house, a little more than half a mile away from the Treu residence.

“Oh, my God! Pack up the dogs, there’s a fire there!” Ms. Numbers-Stefl yelled to her husband. The flames along Lahainaluna Road inched closer, she said, 100 yards away, then 30 — “a freight train coming down the mountain,” in her husband’s words.

“When I turned around, it was right there — that’s how fast it was,” said Mr. Stefl, 67, a longtime resident who rebuilt after his home was destroyed on the same land in a 2018 wildfire. He said he and his wife “literally ran down the stairs, grabbed cats and dogs and backed up the drive through black smoke, fire, heat, just flying through.”

Had the authorities sent them any alerts or warnings?

“Oh, hell no.”

From land and sea, people stood stunned as the once-flickering grass fire near Lahainaluna Road appeared to balloon into a monster. In the upper floor office at his coffee warehouse in the center of Lahaina, next to a chocolate factory and a liquor store, J.D. Sheveland, 58, eyed the firestorm through his window as he paid bills and did paperwork.

The wind sent wooden pallets flying across parking lots, he said, and tore pieces from the new affordable housing complex. He looked toward the northeast at 3 p.m. and, like Ms. Denton Fuqua, saw wisps of smoke rising.

At 3:25 p.m., Mr. Sheveland captured footage of gray smoke starting to flow over the residential streets. Within 20 minutes, his video clips showed the smoke growing ever darker. In a video shot at 3:49 p.m. and posted on the photo sharing website Imgur days later, cars could be seen driving through clouds of smoke on Honoapiilani Highway in the direction of downtown Lahaina.

By 4:14 p.m., Mr. Sheveland, still in his office, could see flames leaping above the rooftops of homes as the blaze tore through the neighborhood, edging closer to the waterfront.

Tourists were left in confusion. At the landmark Lahaina Shores Beach Resort, Breanna and Glenn Gill had arrived for their vacation to discover that the power was out and that there was no cellphone service, but they had not heard about the fire; the guests and staff seemed to have even less information than they did.

At 4:17 p.m., they said, an emergency alert blared from their phones, awakening them from a nap and informing them of the fire for the first time. “Evacuate your family and pets now, do not delay,” it read. “Expect conditions that may make driving difficult.”

The Gills credit the message with potentially saving them from disaster. Even as they fled the hotel, other people were checking in. As they drove toward Kahului Airport — a slow, gridlocked drive that included dodging downed power lines — they saw a few tourists on the side of the road going swimming.

“It was very clear nobody had any idea how dangerous the coastline was at this point, or how dangerous the road conditions were,” Ms. Gill said. She believes they were quicker to leave because they are both from the Western United States and familiar with how dangerous and fast-moving wildfires can be.

Still, she wonders: What if they had turned their phones off?

As Ms. Denton Fuqua and her husband fled their house, police officers directed them away from the main arteries out of town and toward Front Street, the historic commercial street that runs along the ocean. Cars were bumper to bumper, and moving at a crawl. Electrical wires flailed overhead and the smoke was choking.

Finally, they decided to leave their cars in a garage and ran toward the ocean, hoping for clearer air. But debris was flying and small fires were cropping up around them, so they jumped into a stranger’s car for a brief respite from the smoke. Again they got stuck in traffic; again they got out.

By 5:15 p.m., they were cowering between a magic shop and a pizzeria on Front Street, a raging fire and a wall of smoke behind them. In front of them was a long line of cars, gridlocked, and then a short stone wall, and then the ocean. They tried to breathe through their shirts to mask the smoke.

Nearby, firefighters arrived to confront the fire near Mr. Sheveland’s coffee warehouse. As soon as they were gone, flames kicked up again in a field across the street. He grabbed a fire extinguisher and rushed outside. “I’m standing out there trying to put the little fire out and I start hearing, like, a jet engine,” he remembered. “The fire was sucking wind in. It turned into a firestorm right then and there.”

At around 5:30 p.m., he made a run for it. He climbed into his Dodge pickup and, in a caravan of three vehicles carrying seven employees and relatives, dashed down Keawe Street, just off the bypass road, toward the main highway. But the highway was closed, he said, covered with live power lines. Stuck, he turned toward the ocean, jumped the curb, rolled over a grassy area and into a Safeway parking lot.

He soon realized that the only road out of town was Front Street — but hardly anyone was getting out of town that way. Traffic would move a little bit and stop, move and stop.

In his rearview mirror, he could see the firestorm sweeping into Lahaina. Somehow, around 6 p.m., the cars began moving. He escaped.

By then, dozens of people, barely able to see through the smoke along Front Street, were perched on the edge of the sea wall, struggling to breathe.

“We couldn’t see people, but I heard people throwing up, screaming,” said Ydriss Nouara, a sales manager at a local hotel who was fleeing on a scooter with a neighbor. He said he watched as a pit bull threw itself into the water. He called 911, and the operator urged them to get into the water, too.

He watched from a jetty as boats in the harbor caught on fire and swirled around in circles, their masts ablaze.

Ms. Denton Fuqua and her husband had also clambered into the ocean. “We were with a bunch of people praying — kids were crying,” she remembered. “People were letting their pets go because they couldn’t carry them and cover their mouths.”

It was so dark that, at times, she could not see her husband, right next to her. Dozens of strangers floated around her, some holding planks to remain afloat. Embers would land in their hair and they would dunk their heads underwater to avoid catching fire.

“It was like a flamethrower on the town,” she said. “It was as if some person or mythical thing had a blowtorch and was just taking it to our whole entire town.”

Finally, they swam northwest along the shore to Baby Beach, a local landmark, and managed to reach safety.

By that time, a 45-foot Coast Guard cutter had approached the Lahaina breakwater, a little after 6 p.m. It was slow going: The smoke was so thick that the coxswain could not see the bow of the ship.

As they eased in, trying to avoid running aground in the wind and waves, the crew began casting rope lines through the smoke, feeling some of them grow taut as people grabbed them on the other end. They pulled them in. Seven people were saved.

Reporting was contributed by Mike Baker, Tim Arango, Robin Stein, Alexander Cardia, Michael Levenson and Jin Yu Young. Natalie Reneau and Aaron Byrd contributed video production. Kirsten Noyes, Jack Begg and Susan C. Beachy contributed research.