This Feb. 19, 2016, satellite image released by NASA Goddard Rapid Response shows Cyclone Winston in the South Pacific Ocean. The Pacific island nation of Fiji was hunkering down Saturday as a formidable cyclone with winds of 300 kilometers (186 miles) per hour bore down. (NASA Goddard Rapid Response/NOAA via AP)

The Pacific island nation of Fiji was hunkering down Saturday as a formidable cyclone with winds of 300 kilometers (186 miles) per hour bore down.

Cyclone Winston was forecast to pass between the two main populated islands overnight. Many domestic and international flights were canceled and authorities urged to secure their homes and not venture outside.

Prime Minister Voreqe Bainimarama wrote on Facebook on Saturday that the island's evacuation centers were operational and that the government was prepared to deal with a potential crisis.

"As a nation, we are facing an ordeal of the most grievous kind," he wrote. "We must stick together as a people and look after each other."

He said he was concerned some people in the cities weren't taking the threat seriously enough.

The U.S. Joint Typhoon Warning Center said gusts from the were reaching 360 kph (224 mph).

The Fiji Times newspaper reported some damage, including a roof being blown off one home, from some of the nation's smaller islands to the east as the cyclone began to strike there.

The Times said there had been a run on supermarkets and stores as people stocked up on essential supplies and that a 5 p.m. curfew had been placed on all public transportation, including buses, minibuses and taxis.

In this image made from video, residents board up windows as they prepare for the arrival of Cyclone Winston on Saturday, Feb. 20, 2016, in Nadi, Fiji. The Pacific island nation of Fiji was hunkering down Saturday as a formidable cyclone with winds of 300 kilometers (186 miles) per hour bore down. (TVNZ via AP Video)

Many people were hoping the cyclone's path would remain as forecast and thread between the islands of Vanua Levu to the north and Vitu Levu to the south, which is home to the capital, Suva, so that both would avoid a direct hit.

Fiji is home to about 900,000 people.

In this image made from video, residents board up windows as they prepare for the arrival of Cyclone Winston on Saturday, Feb. 20, 2016, in Nadi, Fiji. The Pacific island nation of Fiji was hunkering down Saturday as a formidable cyclone with winds of 300 kilometers (186 miles) per hour bore down. (TVNZ via AP Video)