Firefighters from Hampshire and Isle of Wight Fire and Rescue Service were called to assist paramedics to gain entry at 2.47 am after reports of an unconscious person.
Shortly after paramedics arrived they saw smoke coming from the property and heard explosions within the property, fire crews extinguished the fire just after 3.30 am.
Hampshire and Isle of Wight Fire and Rescue Service investigators are at the property also with officers from Hampshire Constabulary, the circumstances of the fire are currently unknown.
Hampshire Constabulary are now managing the incident due to sensitive information.
More to follow.