FORT MYERS, Florida (REUTERS) - US President Donald Trump viewed flood damage and handed out sandwiches to victims of Hurricane Irma in Florida on Thursday (Sept 14) as utility workers redoubled their efforts to restore power after eight retirees died in a sweltering nursing home.

A hurricane formed off the southwestern coast of Mexico, meanwhile, triggering warnings of life-threatening storm conditions in areas still recovering from a devastating earthquake last week.

Speaking to reporters in the city of Fort Myers on Florida's west coast after a briefing on recovery efforts, Trump lauded the authorities and residents for their preparedness.

"And while people unfortunately passed, it was such a small number that nobody would have - people thought thousands and thousands of people may have their lives ended," he said.

Trump said restoring electricity in Florida was a priority following the storm, which left at least 20 people dead in the southern US state, including the eight retirement home residents in Hollywood, north of Miami.

"There are more electrical people in this state, I think, than ever accumulated anywhere in the world," the president said, referring to the scores of repair teams that have poured in from several states.

"It's going way ahead of schedule - weeks ahead of schedule."

Trump noted that the Florida Keys, the string of tourist islands off the southern coast of the state, had been particularly hard hit and recovery efforts there may take longer.

"That's a very, very special problem," he said. "That was just dead-center, but we're working very hard on that. And we have a lot of goods out there, a lot of water, a lot of food, a lot of everything."

More than 2.6 million people were still without electricity on Thursday, according to the authorities, four days after Irma made landfall in the Florida Keys as a powerful Category Four storm.

Florida Governor Rick Scott said "every person in our state wants their power back" and "we're working hard to get our power back on."

Scott, who toured a flooded neighborhood in Naples, south of Fort Myers, with Trump and his wife, Melania, said efforts were also being made to alleviate gas shortages.

"We're short of fuel," he said. "We still have lines at our gas stations." .

HURRICANE MAX THREATENS MEXICO

In Naples, Trump and the First Lady stood beneath a tent to hand out sandwiches wrapped in cellophane and bottled water to residents and recovery workers.

The president first struggled to put on a pair of white gloves.

"They're too small," Trump said after the glove on his right hand ripped.

Florida authorities were conducting a criminal investigation meanwhile into the eight deaths at the Hollywood nursing home, which had been without air conditioning since Irma struck.

Governor Scott said Wednesday he was "absolutely heartbroken" to learn of the "unfathomable" deaths at the retirement facility and promised to "aggressively demand answers."

Three of those who died were in their nineties, including 99-year-old Albertina Vega. The youngest victim was 70, according to the Broward County Medical Examiner's office.

As Trump visited Florida, French President Emmanuel Macron wrapped up a visit to the French overseas territories of Saint Martin and Saint Barts, two Caribbean resort islands devastated by Hurricane Irma.

The storm left around 40 people dead in the Caribbean before churning east and pounding Florida.

France, Britain and the Netherlands have been criticised for the pace of relief efforts in their overseas territories amid widespread shortages of food, water and electricity.

British Foreign Secretary Boris Johnson visited the British Virgin Islands and Anguilla on Wednesday and pledged "absolute commitment" to Britons there.

The Miami-based National Hurricane Centre (NHC) said meanwhile that Hurricane Max was moving eastward just south of the resort city of Acapulco and could make landfall later Thursday.

The NHC warned that Max, now a Category One storm, could strengthen before it reaches the coast.

"Maximum sustained winds are near 130kmh with higher gusts. Some strengthening is expected today before Max reaches the coast this evening or tonight," it said.

Authorities declared a hurricane warning for 480km of Mexico's coast, stretching from Zihuatanejo to Punta Maldonado.

Guerrero state and western parts of neighbouring Oaxaca state were forecast to receive five to 12.5cm to 25cm of rain, with some areas receiving more than 50cm.

Oaxaca is still struggling to recover after it bore the brunt of the damage from an 8.2 magnitude earthquake that struck Mexico only last Thursday, leaving 96 people dead.