At 1.08 this morning (5 May) Police were called by the fire service to reports of a serious house fire on Kingsdale Drive, Bradford.
A woman and three children managed to escape the property and were taken to hospital for treatment.
Their injuries are not life-threatening.
A fourth child was found inside the address and was sadly pronounced deceased at the scene.
A scene is currently in place at the address and police are working with the fire investigators to establish the exact cause of the fire.