Saudi civil defense authorities say one person has been killed and 30 were wounded when a fire broke out at a residential complex used by the state oil giant Saudi Aramco.

Aramco said the fire started early Sunday in the eastern city of Khobar. It says an investigation has begun into the cause of the blaze.

The Interior Ministry's General Directorate of Civil Defense said the casualties involved victims of various nationalities, without elaborating. Like many companies in the Gulf, Aramco relies on migrant laborers to help bolster its workforce.

Images posted by witnesses on social media showed thick smoke pouring from the large multistory complex as helicopters hovered overhead.

Khobar was the site of a deadly 1996 truck bombing at a dormitory for U.S. Air Force personnel.