Search and rescue volunteers have located hundreds of people reported missing after Hurricane Michael tore through their Florida Panhandle communities, but the death toll of at least 18 is still expected to rise.

Rescue crews heard cries for help and cut into a mobile home crumpled by the storm in Panama City, freeing survivors who had been trapped inside for two days, Matthew Marchetti, co-founder of the Houston-based CrowdSource Rescue, said on Saturday.

In door-to-door searches, teams consisting mostly of off-duty police officers and firefighters have found more than 520 of the 2,100 people reported missing since Michael crashed ashore near Mexico Beach, Florida, on Wednesday as one of the most powerful storms in US history.

“We expect that number to go up dramatically today,” Marchetti said, adding hopes were raised by an influx of volunteers on the weekend and the restoration of power in some areas.

“Volunteers are working side-by-side with first responders. They are cutting holes in roofs. They try to take a picture so we can call the family and tell them we made contact,” he said.

But as roads were cleared to allow wider searches, the death toll was expected to mount. As of early Saturday, authorities were reporting at least 18 deaths in Florida, Georgia, North Carolina and Virginia.

Mere days ago a neat family stood on this Florida site. Now, like hundreds of other dwellings, it is rubble. Photo: AP/ Gerald Herbert

Rescue teams, hampered by power and telephone outages, used cadaver dogs, drones and heavy equipment to hunt for people in the rubble.

In Callaway, Florida, an especially hard-hit town, Catholic Christians barbecued hamburgers and Scientologists handed out water.

“I’m homeless,” said nursing assistant Carla Covington, 45, who is caring for her mother and two children after their house was destroyed by falling trees.

She said it felt good to receive comfort, but was also hard.

The giant tropical storm, which grew in less than two days into a Category Four hurricane, tore apart entire neighbourhoods.

More than 1,700 search and rescue workers have so far been deployed, including seven swift-water rescue teams and nearly 300 ambulances, Florida Governor Rick Scott’s office said.

Power and phone service were being slowly restored on Saturday, with about 236,000 homes and businesses still without power in North Carolina, down from a peak of more than 600,000, said spokesman Keith Acree of the North Carolina Department of Public Safety.

But it could be weeks before power is restored to the most damaged parts of Florida, officials have warned.

-AAP