Authorities have also since separated Nadi and Lautoka which have been in lockdown since a week ago when it was discovered a soldier had contracted the virus and infected a hotel maid in a breach of protocol.
Of the four new cases, three are in the western division, all stemming from the soldier at the managed isolation and quarantine (MIQ) facility, but one case - of a woman in Makoi, outside the capital city - has authorities concerned.
The woman and her husband have since been taken into its isolation facility.
Health Permanent Secretary Dr James Fong said the ministry had not yet been able to "pin down the movements of these people and identify all their contacts".
Forced to take strict precautionary measures against the possibility that the virus had spread, the Government will lock down the capital city and the nearby towns of Lami, Nasinu and Nausori.
"Once we receive further information regarding the Makoi case, there will be appropriate variations to these measures," Fong said.
"We have experienced this situation before, so it should be familiar to everyone. Our purpose is to keep people from circulating unnecessarily. If people don't move, the virus won't move."
While people can leave their homes and access essential services and supermarkets, the Government continues to remind Fijians to avoid large social gatherings and stay indoors. However, it has not made it mandatory for people to stay indoors.
"Your interactions should be limited entirely to those already living in your households. If you're missing a friend or loved one, do the safe thing and call them on the phone.
"If you need to walk around or exercise you may do so, but wear masks and maintain social distance when you must be out," Fong said.
Fiji now has had 91 cases, 24 active (10 contracted in the community; 14 in MIQ), with 65 recovered and two deaths.
- RNZ