A car bomb blamed on the Basque separatist group ETA exploded in central Madrid early today, injuring 14 people just one day before bitterly contested elections in Spain's northern Basque region.
An anonymous caller in the name of ETA warned authorities eight minutes before the blast, Interior Minister Mr Mariano Rajoy said.
The bomb went off in one of the Spanish capital's busiest roads, Goya Street.It could have been a massacre, Mr Rajoy told reporters at the scene. Local media reported the car contained around 30 kg (66 lbs) of explosive.
A security guard was the only one seriously hurt, though his wounds were not life-threatening and all other injuries were minor, emergency services officials said.
The explosion demolished the facade of a nearby bank, shattered windows throughout the area and left the twisted remains of the car littering the street.
The bomb went off virtually on the stroke of midnight as campaigning for the Basque parliamentary ballot officially ended and a Day of Reflection - free of electioneering and opinion polls - was getting under way.
The elections have been overshadowed by ETA's campaign of bloodshed. The group has claimed 29 killings since ending a ceasefire in December 1999 and was blamed for the fatal shooting last Sunday of a senator from Spain's ruling Popular Party (PP).
ETA did not claim responsibility for the latest bombing - it usually waits weeks to do so. But politicians across the spectrum immediately blamed the guerrilla group.
Officials believe the latest attack was intended not only to intimidate Basque voters but also to press ETA's strategy of creating a climate of fear throughout Spain.
The candidate for the government's Popular Party Mr Jaime Mayor Oreja told state radio that Sunday's vote provided an immediate opportunity for the Basques to answer ETA.