Wildfires whipped by hurricane winds triggered evacuations in parts of Hawaii on Wednesday with the Coast Guard rescuing some residents forced into the ocean to escape the smoke and flames, officials said.

Lieutenant Governor Sylvia Luke issued an emergency declaration and told CNN that the hospital system on the island of Maui "was overburdened with burn patients, people suffering from inhalation."

Luke did not provide any figures on the number of injured but said "the reality is that we need to fly people out of Maui to give them burn support."

"911 is down. Cell service is down. Phone service is down. And that's been part of the problem," she said.

Luke, who activated the National Guard to help respond to the fires, said evacuations were underway on Maui but she did not have figures for the number of people who have been forced to flee their homes.

The worst damage appeared to be in the tourist town of Lahaina on the northwestern tip of Maui, one of a number of islands which make up the US state in the Pacific.

Video posted on social media by residents showed fast-moving blazes tearing through the town and sending up huge plumes of black smoke into the air.

"People are jumping into the water to avoid the fire," US Army Major General Kenneth Hara told Hawaii News Now. "The Coast Guard is providing support as we speak."

The Coast Guard said it had "successfully rescued 12 individuals from the waters off Lahaina" and it was sending other vessels to Maui.

Tiare Lawrence, a resident of Lahaina, said she was trying to reach her family members.

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

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

Luke, the lieutenant governor, said the fires were caused by dry conditions and the powerful winds from Hurricane Dora, which is hundreds of miles south of the islands and is not expected to make landfall.

She said the fires have burned hundreds of acres and were being fanned by winds up to 80 miles (130 kilometers) per hour.