Fire crews were called to the single-story home on Crater Lake Avenue just before 7 a.m.
When they arrived on scene they had fire showing out the front window of the living room and the doorway and fire out the back.
One person was treated for smoke inhalation, and the fire department says the home may not have had working smoke detectors.
The building is likely a total loss. The 5 adults who live there are receiving help from the Red Cross.
Medford Fire-Rescue said they’ve determined that the fire originated on the stove top in the kitchen, where a burner was left on and ignited combustible items that were left on the stove top.