Two massive explosions at Russia’s Raspadskaya mine, east of Moscow, have left 30 people dead and 60 people missing.

The first explosion, believed to have been caused by a methane buildup, went off just before midnight Saturday and the second occurred just over three hours later killing a number of rescue workers and injuring at least 58 people.

The second explosion – more powerful than the first – destroyed the main air shaft and the mine’s above-ground structures, halting search operations for most of the day due to high methane build-up.

More than 500 rescue workers have been struggling to ventilate the mine and rebuild shafts so the search operation for those trapped can resume, according to

The Raspadskaya mine is the largest underground mine in Russia with reserves of about 450 million tons of coal. It produced 8.9 million tons of coal in 2007.