On 25 April 1987, ETA attacked the local headquarters of the Socialist Party (Casa del Pueblo) in Portugalete with petrol bombs. One of the petrol bombs exploded beside Félix Peña Mazagatos’s feet, setting light to his clothes. He eventually died on 5 May 1987 as a result of the severe burns he had suffered in the attack. The attack was carried out by a group of street terrorists, self-styled Mendeku. Félix Peña Mazagatos was 55 years old and was from Portugalete (Vizcaya). He was unmarried. He worked in the La Naval shipyard, owned by Astilleros Españoles, in Sestao, and was a member of the UGT trade union.
Eyewitnesses to the attack spoke of horrific scenes, as people ran out of the building engulfed in flames.