"As firefighting efforts continue, 17 additional fatalities have been confirmed today amid the active Lahaina fire. This brings the death toll to 53 people," Maui County said in a statement.
Earlier, Hawaii Governor Josh Green said the death toll would rise "very significantly" as rescue operations continue.
Dozens were left injured as they made desperate attempts to flee the flames and over 270 buildings were damaged or completely destroyed, officials said.
US President Joe Biden on Thursday declared the wildfire as a "major disaster," pledging federal funds for the devastated island of Maui.
A White House statement said the federal aid dedicated to the disaster aims to "supplement state and local recovery efforts in the areas affected by wildfires."
Many historical sites were destroyed in the town in west Maui, officials said. Losses include buildings along Lahaina's historic Front Street and a giant Banyan tree that was imported to the island from India in 1873.
Aerial video showed columns of smoke and haze raging in the 12,000-resident town of Lahaina, a top destination for tourists. Many of the hotels were badly damaged as well.
Ed Sniffen, Hawaii's state transportation director, said that 11,000 tourists flew out of Maui on Wednesday, with another 1,500 expected to leave Thursday.
Rescue operations underway in Hawaii
Officials are yet to complete their assessment of damage and rescue workers are continuing the relief work in the US state.
"We are still in a search-and-rescue mode and so I don't know what will happen to that number, " Bissen said.
Power outages and disruptions in telephone services further aggravated the situation as they impeded evacuation efforts. Communication with the west side of Maui was only available via satellite, Lieutenant Governor Sylvia Luke said.
The smoke and flames rising from the fire forced thousands to evacuate and some people to flee into the sea.
The Coast Guard confirmed it had "successfully rescued 12 individuals from the waters off Lahaina" and it was sending more ships to Maui.
Biden shared his condolences and in a statement said that he has ordered "all available Federal assets on the Islands to help with response."
What started the Maui fires?
The fires started Tuesday, and was exacerbated by a dry brush and heavy wind. The exact cause has yet to be pinpointed.
Robert Watson, the former chair of the Intergovernmental Panel on Climate Change (IPCC) told DW that climate change has raised the risk of wildfires around the planet.
"We're seeing changes in precipitation patterns. We're seeing floods in some areas and droughts in others. What we see is a combination of droughts, meaning various forests are dry, they have a lot of fuel. And when you then start to get high temperatures and high winds, they're the perfect conditions," Watson said.
"We've seen them in Canada. We've seen them in Greece. We're now seeing in Hawaii. These are the sorts of effects we're going to see in forests all around the world," he added.
According to the National Weather Service, Hurricane Dora could be blamed for the rushing wind which fanned the flames.
The storm was passing to the south of the island at a safe distance of 500 miles (805 kilometers).
Sylvia Luke, the state's lieutenant governor, said the fires have burned hundreds of acres and were being fanned by winds up to 80 miles per hour.
Officials had issued a weather service wind advisory which was in effect until Thursday morning.
rm,mfa/sms,wmr (AFP, AP, Reuters)