 On 11 March 2004 a number of terrorist bombs exploded on busy commuter trains in Madrid by Islamic extremists linked to Al-Qaeda, killing 191 persons and injuring thousands.The election, held three days after the attacks, was won by the PSOE, and José Luis Rodríguez Zapatero replaced Aznar as prime minister.As José María Aznar and his ministers at first accused ETA of the atrocity, it has been argued that the outcome of the election has been influenced by this event.