Hillsborough County Fire Rescue spokeswoman Jessica Damico said when Duvall arrived, there was nothing left of the bedroom.
"There was no furniture. All he saw was a piece of the mattress sticking up," she said.
"We put engineering equipment into the sinkhole and didn't see anything compatible with life," Damico said. "The entire house is on the sinkhole."
Neighbors on both sides of the home have been evacuated.
Hillsborough County Sheriff's Office spokesman Larry McKinnon said authorities asked sinkhole and engineering experts, and they were using equipment to see if the ground can support the weight of heavy machinery needed for the recovery effort.