An explosion ripped through a coal mine in Kazakhstan on Friday killing at least seven miners and leaving 23 others missing, a regional governor said. A rescue operation was under way at the Abay mine in the central Karaganda region, said governor Nurlan Nigmatulin. The district hospital said it admitted five miners with serious burns and other injuries, and three of them were in critical condition. The Abay mine is one of eight owned in this Central Asian nation by the world's largest steel-maker, Arcelor Mittal. The mines are part of a complex that includes the Temirtau smelter, one of the world's largest steel plants. In 2006 an explosion at another Mittal-owned coal mine killed 41 people. Authorities concluded the blast occurred as a result of safety rule violations.