Residents have rolled back into the wildfire-ravaged city of Gatlinburg, Tennessee, to get a first look at what remains of their homes and businesses, as officials raised the death toll to 13.

Sevier County mayor Larry Waters also increased the number of buildings damaged, saying it now approaches 1,000.

"I can't describe to you the feelings we have over this tragedy," he said during a news conference with the governor and US senators.

Officials said a Memphis couple, Jon and Janet Summers, both 61, were among the dead.

Their three adult sons became separated from their parents during the wildfires and the three men were severely injured. They were taken to hospital in Nashville, and one has since been released.

The dead also included a couple from Canada and another woman who was on holiday. Officials have not identified the other victims, but did say one person appeared to die of a heart attack while fleeing the flames.

Local officials bowed to pressure from frustrated property owners to allow people back into most parts of the city. Residents have to pass through a checkpoint and must show proof of ownership or residency, Gatlinburg city manager Cindy Cameron Ogle said.

"The city is not implying that private property is safe," she said. "People may encounter downed powerlines or other hazards."

Among those waiting to return was Tracy Mayberry. He and his wife, 12-year-old son and five dogs have moved between hotels since they were forced to evacuate their rental home on Monday night.

They struggled to find a place to stay on Thursday as many lodges began to discontinue special rates for evacuees.

"It feels like Gatlinburg is more worried about how to rebuild than they are about their people," he said.

In nearby communities, there were signs of normality. In Pigeon Forge, the Comedy House rented an electronic billboard message that said it was open. A hotel flyer urged guests to check out the scenic Cades Cove loop: "Take a drive and remember what you love about the Smokies!"

Dollywood, the amusement park named after country star Dolly Parton, was reopening after it was spared any damage.

In the Great Smoky Mountains National Park, a forest of bare trees standing amid a scorched landscape could be seen along with fire crews sawing a tree stump.

In Gatlinburg, the centre of the devastation, officials hope to open the city's main roads to the public by Wednesday.

Authorities searching the charred remains of homes and businesses said they expected to finish by nightfall on Friday.

Despite recent heavy rain, fire officials warned people should not have a false sense of security because months of drought have left the ground bone-dry, and wildfires can rekindle.

The damage began on Monday when a wildfire, probably caused by a person, spread from the Great Smoky Mountains National Park into the Gatlinburg area as hurricane-force winds toppled trees and power lines, blowing embers in all directions.

Gatlinburg Fire Chief Greg Miller said: "We had trees going down everywhere, power lines, all those power lines were just like lighting a match because of the extreme drought conditions. So we went from nothing to over 20-plus structure fires in a matter of minutes. And that grew and that grew and that grew."

More than 14,000 residents and visitors in Gatlinburg were forced to evacuate, and the typically bustling tourist city has been shuttered ever since.

National Park superintendent Cassius Cash said the fires were "likely to be human-caused" but he has refused to elaborate, saying only that the investigation continues.

Agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives are helping investigate.