The Gresford disaster occurred on 22 September 1934 at Gresford Colliery, near Wrexham, in northeast Wales, when an explosion and underground fire killed 266 men. Gresford is one of Britain's worst coal mining disasters: a controversial inquiry into the disaster did not conclusively identify a cause, though evidence suggested that failures in safety procedures and poor mine management were contributory factors. Further public controversy was caused by the decision to permanently seal the colliery's damaged districts, meaning that only eleven of those who died were recovered.