The house, in Lythwood Road, Bayston Hill, Shrewsbury, was left severely smoke and fire damaged.
Crew manager Duncalan McLoughlin, of Shrewsbury Fire Station, said an investigation has been launched after the fire that it thought to have started in a bedroom on the first floor shortly before 11.20am on Saturday.
“On arrival we found a fully developed fire inside the property,” he said.
“The three occupants were outside when we arrived. It took us some time to get the fire under control.
“The property had suffered extensive damage in all the rooms. It started in an upstairs bedroom.
"An ambulance was called to give the householders a check up. They will have to find somewhere to stay.”