Rescue workers and volunteers are searching for more than 1300 people still missing in the Florida Panhandle after the area was devastated by Hurricane Michael last week.

Tens of thousands of residents also remain without power.

At least 19 deaths in four states have been blamed on Michael, which made landfall on Wednesday and is one of the most powerful storms on record to hit the continental United States.

Volunteer rescue organisation CrowdSource Rescue said its teams were trying to find 1300 people still missing in the disaster zone in the Panhandle, according to Matthew Marchetti, co-founder of the Houston-based group.

An estimated 30 to 40 people remained unaccounted for at Mexico Beach, according to a city councillor, Rex Putnal.

Members of Florida Task Force Two Search and Rescue continue their work searching the devastation left at Mexico Beach. Photo: Getty

The town of about 1200 residents took a direct hit from the hurricane.

The town’s mayor has said that at least one person was killed, while CNN reported that another person was found dead on Monday.

With most Mexico Beach homes already searched for survivors, rescue workers used dogs to find any bodies that might be buried under the debris.

Volunteers help distribute food, water, cleaning supplies and other necessities at an aid distribution point in Panama City, Florida. Photo: Getty

More than 150,000 people were still without power in the US Southeast, with residents of battered coastal towns such as Port St. Joe, Florida forced to cook on fires and barbecue grills.

At least 85 per cent of customers in four mainly rural Panhandle counties were without electricity on Monday.

Officials said it could be weeks before power returns to the areas that sustained the most damage.

With top sustained winds of 250km/h, Michael hit the Florida Panhandle as a Category 4 hurricane on the five-step Saffir-Simpson scale on Wednesday.

Here’s the story behind the story on how we ended up writing about the Sand Palace of Mexico Beach, the last beachfront house standing on its block after Hurricane Michael (thread!): https://t.co/bzKio2Yfbm

— Patricia Mazzei (@PatriciaMazzei) October 15, 2018

The winds and storm surge caused insured losses worth between an estimated $US6 billion and $US10 billion, risk modeller AIR Worldwide said. Those figures do not include losses paid out by the National Flood Insurance Program or uninsured property, AIR Worldwide said.

Water supply was restored to some in Panama City on Monday but Bay County officials said it was not yet safe to drink.

US President Donald Trump and First Lady Melania Trump visited the storm-affected areas on Monday, arriving by helicopter.

They distributed bottles of water at an aid centre in Lynn Haven, a city of about 18,500 people near Panama City in northwestern Florida.

“To see this personally is very tough – total devastation,” said Mr Trump, who later travelled to neighbouring Georgia to see storm damage there.