The targets were a convoy of civil guards who were escorting workers and weapons from the nearby Esperanza y Cia Arms factory to Bilbao.

When they repeated this with the second vehicle, two ETA members, Gregorio Olabarría Gorrotxategui Bengoa and Javier Argote, were killed as a result of injuries suffered when they failed to escape in time before the grenades exploded.

[3] Having been alerted by a local resident who had heard the gunfire and explosions, the police arrived on the scene at 9:00 am and found a large quantity of grenades, 9 millimetre ammunition and guns of Belgian origin.

[6] On 25 June 1982, five people, Francisco Esquisavel, Angel Recalde, Jesús Trocaola, Juan Ramón Ibarlueca, Ana Guerenabarrena and María Isabel Mendiola appeared in court accused of having participated or cooperated in the attack.

[7] In 1984, Jaime Rementería Beotegui was found guilty of participation in the attack, fined 60 million pesetas, and sentenced to prison.

Jose Luis Ansola Larranaga ("Peio the Elder") was acquitted of involvement in the attack on the basis of lack of evidence.

The Chief Prosecutor, Eduardo Fungairiño, and the Association of Victims of Terrorism had alleged that Ansola had been the author of the operation and had requested 174 years in prison for him.