Hurricane Gonzalo has rolled into Bermuda pulling up trees, cutting power to 70,000 people and damaging the island's main hospital.
Gonzalo approached Bermuda as a Category 3 storm then weakened to Category 2 before coming ashore with sustained winds of 110 mph (175 kph).
Nearly all of the island's roads were impassable and cluttered with debris and fallen trees, police said.
The roof of Bermuda's hospital was damaged and there was also water damage in its new intensive care unit.
Royal Navy ship HMS Argyll, with a crew of some 180 sailors, is expected to arrive on Sunday to help with recovery efforts.
Gonzalo swept by the eastern Caribbean earlier this week, claiming one life in the Dutch territory of Saint Maarten.
It is the second big storm to hit Bermuda in several days after Tropical Storm Fay damaged homes and also knocked down trees and power lines.
"To be struck twice by two different cyclones is unusual, to say the least," said Max Mayfield, a former director of the US National Hurricane Centre in Miami.
Flooding was the main concern on Bermuda, which has one of the highest per-capita incomes in the world and is known for strict building codes that ensure homes can withstand sustained hurricane-force winds.
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Gallery: Hurricane Gonzalo's Path
The latest predicted route of Hurricane Gonzalo sees it travel across the Atlantic towards the UK and Ireland. Pic: NOAA
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Forecasters say a downgraded weather system could hit Ireland in the early hours of Tuesday morning, with this image showing their current margin of error. Pic: NOAA
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Gonzalo could hit the British territory of Bermuda on Friday. Pic: NOAA
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A NASA satellite image shows the hurricane as it departed the Caribbean
"Water damage, especially from the wave action, will take the biggest toll," Mayfield said, noting that seas had risen to between 30 and 40 feet (9 and 12 metres).
Bermuda Harbour radio operator Josh Powell told Sky News: "The closest point of approach was about 25 nautical miles, at about 8pm. That is when the generator tripped and we lost power.
"It was quite scary, being on top of the hill seeing the whole building move."
Mr Powell said it was still too early for evacuated residents to return to their homes.
"It is still gusting 60 knots and is about 100 miles to the east, but it is still quite dangerous for people to go outside," he said.
As the worst of the storm passed, Bermuda governor George Ferguson tweeted that no deaths or serious injuries had been reported so far.
Gonzalo is now heading towards Britain and is expected to bring travel disruption and dangerous driving conditions on Tuesday.
The Met Office said the remains of the hurricane were likely to bring winds of 60mph and heavy rain, particularly in Northern Ireland, northern England, north Wales, southern and eastern Scotland.