On the night of 25 September 1985, Ignacio María Astiasuinzarra Pagola, José Sabino Echaide Ibarguren, José María Echaniz Maiztegui and José Agustín Irazustabarrena Uruzola were having a drink in the bar of the hotel Monbar in Bayonne (France), which was frequented by sympathisers of the Basque nationalist left and ETA members. Around 9.15 pm, when they were standing at the bar, two individuals got out of a car and entered the premises armed with machine guns. One of the terrorists stayed at the door to make sure nobody left the establishment while the other let off a burst of fire at the customers.
Astiasuinzarra, Echaide, Echaniz and Irazustabarrena were killed and a fifth man, a French citizen, was seriously injured. Several witnesses chased the assailants on foot and managed to detain them until the French police arrived. The two men were mercenaries, with links to the Marseilles criminal underworld, who had been hired by GAL.
Ignacio María Astiasuinzarra Pagola, known as Iñaki, alias Beltza, had been a member of ETA since 1972. He was arrested in 1973 and freed by other armed ETA members who burst into the barracks at Loyola (Guipúzcoa).