On 25 April 1987, ETA attacked the local headquarters of the Socialist Party (Casa del Pueblo) in Portugalete with petrol bombs. One of the Molotov cocktails thrown at the socialist headquarters exploded at Felix Peña Mazagatos’ feet, setting his clothes on fire. 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. Eye witnesses to the attack spoke of horrific scenes, as people ran out of the building engulfed in flames.
Socialist party member María Teresa Torrano Francia was killed in the same attack. The following day, the Secretary General of the Socialist Party in Vizcaya, Ricardo García, called for Herri Batasuna to be banned.