Fiji declared a state of natural disaster on Thursday, ordering its entire population to take shelter ahead of a nightly curfew as a potentially devastating cyclone approached the Pacific Island nation.

Residents walk on the street in Suva, Fiji on Wednesday. Photo: VCG

Cyclone Yasa, a top category five storm, is expected to bring winds of up to 250 kilometers per hour and torrential rain across the South Pacific archipelago when it makes landfall overnight.

Still a few hours out from the worst weather, Fiji's Meteorological Service said storm force winds and heavy rains have been recorded in some parts of the country already.

Images shared on social media showed roads blocked by landslides, floodwaters and fallen trees.

By 8 pm (0800 GMT), the center of Yasa is forecast to be 100 kilometers east of the village of Yasawa-i-Rara and potentially over Fiji's fifth-most populous province of Bua, home to 15,000 people, Fiji's National Disaster Management Office said.

Reinforcing the threat, Fiji Prime Minister Frank Bainimarama told the country's near 1 million population to find safe shelter ahead of a 14-hour nationwide curfew beginning 4 pm (0400 GMT).

"The impact for this super storm is more or less the entire country," Bainimarama said in a video posted to Facebook.