An explosion sank a Saudi Arabian tanker in the Persian Gulf, killing six crew members and injuring seven others, authorities reported Friday. The cause of the blast was not known.

Helicopters rescued the remaining members of the 34-man crew.A spokesman for the Dutch salvage company Wijsmuller said the tanker Sagheera sank in the gulf Thursday before salvage tugs could assist it after an explosion sparked a fire on board the vessel.