The scale of devastation left by Hurricane Irma was far greater than anyone expected, Donald Trump has said.

Millions of people are still without power and more than 180,000 are now staying in shelters in Florida after the storm swept through the state on its way to Georgia and South Carolina.

In Jacksonville, Irma brought some of the worst flooding the city has ever seen, with more than 350 people rescued by emergency workers on Monday.

And in the south of the state displaced residents from parts of the Florida Keys are only beginning to be allowed to return home after Irma blocked a major route and cut power, water and communication lines.

Commenting on the scale of the disaster, Mr Trump tweeted: "The devastation left by Hurricane Irma was far greater, at least in certain locations, than anyone thought - but amazing people working hard!"


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Image: A firefighter views a collapsed coastal house after Hurricane Irma passed the area in Vilano Beach, Florida Image: Wrecked boats on Saint Martin Image: A Royal Marine speaks with a local resident in Tortola, British Virgin Islands Image: Daytona Beach, Florida Image: Miami, Florida Image: People sit aboard a plane to leave the island after it was devastated by the hurricane, in Simpson Bay, Saint Martin Image: Naples, Florida Image: Water levels rise, flooding Charleston Harbour, South Carolina Image: Saint Martin Image: Coconut Grove in Miami, Florida Image: Damaged buildings on the British Virgin Islands Image: Jacksonville, Florida Image: Miami Image: Saint Martin Image: A line of utility trucks drive north on Interstate 75 in Florida /

Florida Keys felt the fullest extent of Irma when it made landfall as a category four storm with 130mph winds on Sunday morning.

State governor Rick Scott said there had been "devastation", adding: "My heart goes out to the people in the Keys."

"I just hope everybody survived," he said. "It's horrible what we saw."

Roadblocks have been lifted for residents returning to Key Largo, Tavernier and Islamorada, but the Lower Keys remain off limits.

Corey Smith, a UPS driver who rode out the hurricane in Key Largo, said there was no power on the island and supermarkets were closed.

"They're shoving people back to a place with no resources," he said. "It's just going to get crazy pretty quick."

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Image: Residents living near St Johns River in Jacksonville were told to 'get out now'

Surveyed damage in Jacksonville. @FLGuard will be conducting aerial assessments throughout the day. pic.twitter.com/hBfYm8kpID — Rick Scott (@FLGovScott) September 12, 2017

In the Jacksonville area, police warned residents along the St Johns River to "get out now" amid a heavy storm surge on Monday.

"If you need to get out, put a white flag in front of your house. A t-shirt, anything white," Jacksonville Sheriff's Office said.

Six people in Florida are thought to have died as a result of the hurricane, as well as four in other states.

In the Caribbean, where 35 people died, the effort to return to normality is likely to take longer.

St Martin resident Raju Budhrani, 51, said: "The destruction is on a biblical scale. It's how you see it in the movies. It's actually worse than that."

Hundreds of tourists are still trying to leave the once-paradise island, while looting is now a major concern for the locals.

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Image: The destruction of Hurricane Irma in the Caribbean. Pic: NASA

"We can't sleep in peace because of the thieves," said Yovanny Roque, 48.

Another St Martin resident, Germania Perez, said: "There's no food here. There is no water here."

There are also reports of people who are evacuating the island being forced to leave pets behind.

NASA pictures of the Caribbean, taken from space, show the previously lush green islands now turned a dirty brown.

Another hurricane - Jose - is forecast to closely shave the Turks and Caicos islands towards the end of the week, severely hampering the clean-up efforts there.

On the British Virgin Islands, damage caused by Irma allowed 100 "very serious" prisoners to escape from a jail.

Image: An aerial shot of Florida Keys after Hurricane Irma wreaked devastation

Foreign minister Sir Alan Duncan told the Commons the convicts pose a "serious threat of the complete breakdown of law and order" on the overseas territory.

Sir Alan said Marines from a Royal Navy ship were used to "protect the Governor and everything else about law and order" on Friday.

Foreign Secretary Boris Johnson is travelling to the Caribbean to oversee relief efforts after huge public pressure and after Dutch and French heads of state announced visits to their overseas territories.