Additional expert support has been deployed to Hawaii, where forensic work is continuing to find victims of the devastating wildfires.
At least 89 people are known to have died but there are fears this number will rise further, with hundreds still unaccounted for.
Many more remain in emergency shelters after fleeing from the flames.
Firefighting efforts are continuing in parts of the island of Maui, including around the devastated town of Lahaina.
Jeremy Greenberg, a senior official at the Federal Emergency Management Agency (FEMA), has told the BBC that extra support being sent included urban search and rescue, and fire suppression teams.
"The absolute number one priority is survivor safety," he said.
Mr Greenberg added that while close to 1,000 people are still yet to be contacted, some of these may be safe but out of reach for a number of reasons.
Hawaii Governor Josh Green visited Maui on Saturday and told reporters he was expecting to see "significantly higher numbers" of fatalities in the coming days.
"It will certainly be the worst natural disaster Hawaii ever faced," he said.
"It may be the worst fire that America ever faced."
Sniffer dogs trained to detect bodies have been looking for signs of corpses under the rubble in Lahaina.
There have also been reports of bodies being found around the local harbour, where people have been pulled out alive.
It is thought that more than 2,000 buildings have been damaged or destroyed since the fires broke out. The majority of these were homes in the Lahaina area.
The main road to Lahaina was briefly re-opened to residents on Saturday, before quickly being closed again.
The Kahakuloa road is open, but locals say it's far too dangerous to attempt to drive that way. The road - known simply here as "the backroad" to Lahaina - is barely wide enough for one car, has many hair-pin turns, and a steep drop-off.
"We can't drive this truck there. It's a cliff," said resident Ruth Lee who was stuck in traffic trying to bring supplies to her family that stayed behind.
Residents are furious about the decision to keep the main road closed to the potentially homeless survivors.
Hundreds who fled with proof of their residency are waiting in traffic, hopeful that they will be allowed through. But with the queue of cars stretching for about a mile, and news that the road has shut once again, they don't know whether they'll be forced to turn around.
Liz Germansky, who lost her home in the fire, is angry about the response. "The government's getting in the way of people helping," she says, while sat in the same traffic queue.
The cost of rebuilding Maui has been estimated at $5.5bn (£4.3bn), according to the Pacific Disaster Center (PDC) and FEMA, which is coordinating the relief effort to Hawaii from Washington.
"We're strong people, we're going to be okay," one local resident, Lars Johnson, told CBS News.
"We're going to do what we can to rebuild. And it'll be back and it'll be bigger and it'll be stronger than ever before."
Helicopter pilot Richard Olsten has flown over Maui and told the BBC that even most of the boats in the harbour were burnt and had sunk.
"The historic buildings, the church, the missionary building and so forth - all gone," he said.
"The main tourist area where all the shops and restaurants are, the historic front street - everything burnt to the ground."
Local groups have been trying to organise food, water and shelter for those who have been made homeless with the help of organisations such as the American Red Cross.
Their national spokesperson, Todd James, said that while the focus on now is providing support to survivors, they will eventually help with damage assessment and distributing emergency supplies to help with the clean-up.
As well as receiving aid, people who end up at emergency shelters that have been set up are also able to scan QR codes on their phones to report that they are safe and to alert the authorities that someone they know is missing.
Felicia Johnson, who owns a printing business in the city of Kuhului, Maui, is organising a massive grassroots response to the disaster.
Her family is from the Lahaina area. She has amassed hundreds of pounds of donated supplies to bring in, but has been unable to shuttle them through the government checkpoint.
She says that pleading with authorities to let her enter with her donated goods is the hardest part for her emotionally - not the devastation she has witnessed while dropping off supplies."That's the part that I'm so wrecked on, is I got to keep begging you to come in to feed people."
Many of the docks in the area are too badly damaged or destroyed to bring in supplies by boat, Ms Johnson said. Some people that have made the journey have swum the supplies to the shore.
Some of the young men helping her load supplies blame government mismanagement and bureaucracy.
"Too many chiefs, not enough warriors," said Bradah Young, 25.
"Everybody is in charge but nobody is moving," said another man.
As they departed in hope of being allowed through the checkpoint, one man threw up a shaka, a traditional hand greeting in Hawaii.
Skippy Bailey, who is the regional director for air ambulance company Hawaii Life Flight, said the support Maui was receiving from other islands and the US mainland was "tremendous".
But he added that the task at hand was "daunting" due to the coordination effort it was going to take to get those in urgent need of care to a place where they could receive it.
Complicating the task is the fact that phone and power networks are still disrupted in some areas.
Hawaii's attorney general has announced a "comprehensive review" into how the authorities responded to the wildfires.
It comes as questions mount over whether officials warned residents fast enough and if there were flaws in the early warning system.
Hawaii Electric, the utility that provides service to 95% of Hawaii's residents, has been criticised for not shutting off the power - despite warnings that high winds could create dangerous fire conditions.
Source: BBC
BDST: 0922 HRS, AUG 13, 2023
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