The incident began when five armed members of the United Red Army (URA), following a bloody purge that left fourteen members of the group plus one bystander dead, broke into a holiday lodge below Mount Asama, taking the wife of the lodge-keeper as a hostage. A standoff between Japanese police and the URA radicals took place, lasting ten days. The lodge was a natural fortress, solidly constructed of thick concrete on a steep hillside with only one entrance, which, along with their guns, enabled the hostage-takers to keep police at a distance.