Brian Schatz, a US senator from the state, said on social media that Lahaina is "almost totally burnt to the ground".

At least six people were killed in Maui County, officials said on Wednesday.

Maui's hospital system has been overwhelmed with burn patients and people suffering from smoke inhalation.

"Firefighters are still trying to get the fires under control, and our first responders are in search and rescue mode," Mr Schatz said.

There were reports early on Wednesday that some people jumped into the ocean to escape the fast-moving flames. The US Coast Guard said it rescued at least a dozen people from the water.

Maui County Mayor Richard Bissen Jr said in a news conference that many homes and business structures were completely destroyed.

One resident in the town of some 12,000 people told local media that every boat in the town harbour was burning.

"It looks like something out of a movie, a war movie," Chrissy Lovitt told Hawaii News Now.

Watch: Videos show wildfires tearing through Maui towns

Officials said it is still difficult to determine the true extent of the damage on Maui, and have warned the death toll may rise. Around 2,100 people have been displaced.

Some relatives of people living in Lahaina said they are worried about family members who are missing.

"I still don't know where my little brother is," Tiare Lawrence told Hawaii News Now. "I don't know where my stepdad is."

"Everyone I know in Lahaina, their homes have burned down," Ms Lawrence said.

Images show devastation of Hawaii wildfires
Thousands remain without power or cell phone service due to the fires, and 911 services in West Maui were down on Wednesday.

Officials said that three large fires remain active and out of control on Maui.

Several blazes are also burning on the Big Island, also known as Hawaii island, a neighbouring island to Maui.

The fires have reduced homes, businesses and boats on the harbour to rubble

The National Weather Service said the flames were fanned by Hurricane Dora, which passed Hawaii at a distance but brought with it gusts of above 60 mph (97k/h), coupled with low humidity levels.

President Joe Biden said in a statement that the federal government has sent assistance to Hawaii as it battles the flames and continues with rescue efforts.

He added that the Department of Transportation is working to evacuate tourists from Maui. About 4,000 visitors are trying to leave the island, said state transportation official Ed Sniffen.

The County of Maui has asked visitors to stay away from Lahaina, as roads into the town are closed except for emergency vehicles.

"This is not a safe place to be," said Hawaii's Lieutenant Governor Sylvia Luke.

"Certain parts of Maui, we have shelters that are overrun," Ms Luke added. "We have resources that are being taxed." 

Lahaina is a historic town on the western tip of Maui. Its center dates back to the 1700s and is on the US National Register of Historic Places.

 Watch: Survivors describe harrowing escape from Hawaii wildfires

By Nadine Yousif