The category two cyclone has crossed over the capital of Suva this afternoon but brought extensive flooding to both Viti Levu and Vanua Levu over the past 24 hours with the Rewa River the latest major waterway to burst its banks.
The storm, with average winds near its centre of 100km/h and gusts of up to 140km/h, also downed trees and destroyed crops across large parts of the country.
However the director of the NDMO, Vasiti Soko, said there were still reports of people not being cautious.
"We are in the midst of a cyclone with widespread flooding throughout the country, yet we continue to receive reports of members of the public, adults and children alike wandering around," she said.
"They should be mindful of the risks they place themselves and members of the Fiji police force deployed to rescue them [in] when there is a mishap."
Soko reiterated that people needed to stay home so police could assist with moving Fijians into evacuation centres who needed to be helped.
The NDMO said there are currently around 7600 people occupying 204 evacuation centres around the country.
Cyclone Ana is moving to the south of Viti Levu and is forecast to sweep over the island of Kadavu late tonight or early morning.