The Grupos Armados Españoles (GAE), an armed group operating in the Basque Country in the early years of the Spanish democracy, planted a bomb in a local bar which exploded that evening killing four civilians and wounding ten.
According to a former military man who was a member of one of these groups, they were "supervised by agents of the Spanish secret service, with money and free hands to act as outlaws".
On 20 January 1980, a group of four people coming from a dinner to celebrate their success in organising the Cavalcade of Magi, arrived in Alonsotegi and parked their Chrysler 150 at the bar's entrance.
It was inside a cardboard box placed at the left side of the entrance, next to the main door, and it contained a device with 6 kg of Goma-2 and electric ammunition which was triggered after being lifted or moved, as the first witnesses declared, by Liborio Arana Gómez (57), one of the victims.
Arana's body was "completely destroyed" and his remains were found in the same mound where the half of the car was discovered and in the façade of a nearby house.
[3] The other three victims were the married couple Pacífico Fika Zuloaga (39) and María Paz Armiño (38), from Güeñes, and Manuel Santacoloma Velasco (57), from Alonsotegi.