More than 1,000 acres had been burned and 250 structures were being threatened as of early Thursday morning.
Mandatory evacuations have been issued for some residents in the Swanton Road area.
Only a handful of people went to the evacuation center set up in the city of Davenport.
Officials were going door-to-door warning residents of the blaze. They were concerned they would not reach all residents who did not receive emergency calls that went out to roughly 300 people.
The area is remote, so many people rely on their own well water and backup generators.
There were about 300 firefighters attacking the blaze from the ground Wednesday night into Thursday morning.
As of 1 a.m. Thursday, there were no reports of injuries or homes burned.