Mock coffins, symbolising the 65 miners who died in an explosion at Grupo Mexico’s Pasta de Conchos coal mine, are displayed at the Angel of Independence monument during a protest in Mexico City on February 19 to mark the twelfth anniversary of the disaster, which occurred in the early hours of the morning of February 19, 2006. The mineworkers on the 22:00 to 06:00 shift were trapped underground by the methane explosion, and only two of the bodies were recovered. The explosion took place after mineworkers complained of a gas leak. The oxygen packs allotted to each mineworker only guaranteed six hours of oxygen.