MOSCOW — Rescue workers scrambled Sunday to save 83 people trapped in Russia's largest underground coal mine after two explosions killed at least 12 people and injured dozens more, officials said. Among those trapped were rescue workers who had entered the Siberian mine after the first blast.The second, more powerful explosion destroyed the main air shaft and all of the mine's above-ground structures, the governor of the Siberian region of Kemerovo told Prime Minister Vladimir Putin during a meeting with emergency officials, according to a government transcript.The first blast, believed to have been caused by methane, hit the Raspadskaya mine just before midnight Saturday and the second about 3½ hours later. There were 359 workers below ground at the time of the first explosion, the Emergency Ministry said. A total of 58 people were injured.Most managed to get out, but after the second blast, 64 miners and 19 rescue workers were trapped underground and all communication with them was lost."It's clear the situation is difficult," Putin said "We could even say very difficult, tragic. Dozens of people remain in the mine. ... Their fate is unknown. And the saddest thing is that additional rescuers cannot be sent into the mine right away."There was no immediate information on what set off the blast. Mine explosions and other industrial accidents are common in Russia and other former Soviet republics, and are often blamed on inadequate implementation of safety precautions by companies or by workers themselves.