Maui County Emergency Management administrator Herman Andaya had been heavily criticised by residents and the media over the island's response to the fires.

A statement from Maui County Mayor Richard Bissen said Mr Andaya had resigned because of health reasons.

"Given the gravity of the crisis we are facing, my team and I will be placing someone in this key position as quickly as possible and I look forward to making that announcement soon," Mr Bissen said.

The resignation takes place one day after Mr Andaya made his first appearance in a press conference, which came more than a week after the catastrophe destroyed or damaged 2,200 buildings and caused some $5.5bn (£4.3bn) in damage.

Hundreds of people remain unaccounted for.

Some Maui residents say lives could have been saved had emergency sirens sounded, but Mr Andaya's agency opted against using them, saying they would have been ineffective and confusing.

"The public is trained to seek higher ground in the event that the siren is sounded," Mr Andaya said during Wednesday's press conference, which grew tense at times as reporters questioned the government's response during the fire.

"Had we sounded the siren that night, we're afraid that people would have gone mauka (to the mountainside) and if that was the case then they would have gone into the fire," Mr Andaya said.

The siren system was created after a 1946 tsunami that killed more than 150 on the Big Island, and its website says they may be used to alert for fires.

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Meanwhile, President Joe Biden, who is yet to visit Hawaii, vowed on Thursday that the US government would remain steadfast in its commitment to help the people of Maui recover.

In a brief video, Mr Biden said the federal government had already sent hundreds of emergency personnel, thousands of meals, and essential supplies such as cots and blankets to the devastated town.

"We will be with you for as long as it takes, I promise you," said Mr Biden.

The president plans to travel to Hawaii on Monday to survey the devastation and meet first responders and survivors.

Back in the Pacific Ocean state, Hawaii Attorney General Anne Lopez said in a written statement on Thursday that she will appoint a private, third-party agency to investigate and review how state and county officials responded to the wildfires.

Hawaii Governor Josh Green has tasked Ms Lopez with carrying out a comprehensive review of actions taken before, during and after the wildfires.