Police were called at 12.30pm on December 31 to Banks Road in Crawley to an explosion at a house. Emergency services are at the scene.
It is unclear at this stage what caused the explosion but it is not believed to be suspicious.
Damage is confined to the interior of the house and no other premises are affected.
A woman in her 50s was taken from the house, treated by paramedics but has sadly died at the scene shortly afterwards.
There is not believed to have been anyone else in the house.
Drivers are being asked to avoid the area as there are some road closures while the scene is examined.