More than 3,500 people evacuated to emergency shelters in Fiji as the biggest cyclone in 20 years swept across the Pacific island nation on Monday, three days after the storm killed four people and destroyed thousands of homes in nearby Samoa.

Tourist resorts on many of Fiji's palm-fringed islands have been evacuated and authorities warned people to remain under shelter as Tropical Cyclone Evan battered the country, blowing over trees and destroying houses.

Fiji, home to a population of 890,057, is slightly smaller than New Jersey and is made up of 332 islands, according to the CIA’s World Fact Book.

Authorities said Cyclone Evan had generated destructive winds, torrential rains and was likely to lead to flooding due to a storm surge as it passes to the northwestern side of the main Fiji islands of Vanua Levu and Viti Levu, with wind gusts up to 170 mph.

Fiji's weather bureau said Cyclone Evan was rated a category 4 storm, the second highest level, and was moving only at about 11 mph, meaning the destructive winds could last several hours.

Prime Minister Frank Bainimarama ordered public servants to stay at home and he put emergency services on standby. Hospitals and health centers have been closed for all but emergency patients.

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‘Every Fijian will be affected’
Power supplies have also been cut to some areas as a precaution against falling power lines, including in the main tourist town of Nadi. Airlines grounded flights to and from Fiji, stranding about 1,900 visitors in the country.

Fiji Ministry Of Information / Reuters

Strong waves caused by Cyclone Evan hit the beach on the Fijian island of Suva. Evan was the biggest storm to hit the Pacific archipelago in 20 years.

"I cannot stress enough how serious this is. Every Fijian will be affected but we must take preventative steps now," Bainimarama said.

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Storms of this strength hit the island paradise relatively rarely, with only 12 cyclones measuring category 3 strength or higher recorded in the past 40 years, according to Weather.com.

Residents and businesses stocked up on food and put up shutters to protect shops and offices. Major roads have been closed and authorities are warning that bridges could be swamped by flood waters.

Schools throughout the country were also being used as evacuation centers, with authorities saying more than 3,500 people had sought shelter by late on Monday.

The Fiji Times reported rough seas and ferocious winds had forced a bulk carrier to run aground on a reef near the capital of Suva.

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Australia and New Zealand offered support to Fiji ahead of the storm and have placed search and rescue personnel on standby.

Reuters contributed to this report.

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