The wildfires began Friday and have damaged more than 100 homes in southeast Tasmania, CNN reported.
On Sunday, rescue workers went door-to-door in the towns of Dunalley and Boomer Bay, trying to locate those who have gone missing, officials said.
While there have been no casualties reported, Acting Police Commissioner Scott Tilyard said he was "fearful that someone may have died in this fire."
"It is a very distinct possibility still, and I think people need to brace themselves that that may be the case," Tilyard said.
Meanwhile, the fires have continued, and the Tasmania Fire Service has warned that a wildfire was advancing on Taranna, a small town known for the Tasmanian Devil Conservation Park.
"It is likely to be too late to leave the area. If you home is well constructed, prepared and actively defended, it may provide shelter," the fire service said in a emergency warning message issued Sunday.