Mercer County Coroner Ron McNall says investigators sifting through the wreckage of the home in the village of Sherrard believe one more person was killed in the blaze, but they have yet to recover the body.
He says two people who escaped the fire told authorities there were five others still inside - two adults and three children.
The fire broke out around 1 a.m. Wednesday at the home in a rural area on the edge of Sherrard, which is about 10 miles south of the Quad Cities.
Authorities were using heavy equipment and digging by hand to try to recover the last body.
McNall says investigators haven't determined what caused the blaze.