Crews from Dogsthorpe and Stanground were called to a house fire in St Olaves Drive, Eye.
Two firefighters wearing breathing apparatus used a hose reel to extinguish a fire and positive pressure ventilation fans to clear smoke from the property.
Two casualties were taken to hospital by ambulance to be treated for smoke inhalation.
Crews returned to their stations by 3.25pm.
The cause of the fire was deliberate. A 21-year-old man from Eye has been arrested on suspicion of arson.