Seven police were injured when a massive bomb exploded in the northern Spanish city of Bilbao today.
The Basque separatist group ETA said they planted the device outside an office of Spain's governing Socialist Party on the outskirts of the Basque region's main city.
The group made a phone call saying where and when the blast would occur, a police official said.
Seven officers who were helping to evacuate people and cordon off the zone were slightly injured in the blast.
It caused heavy damage to the party office, apartment buildings and cars in the suburb of La Pean.
ETA is one of the main challenges facing Socialist Prime Minister Jose Luis Rodriguez Zapatero as he begins his second term in office.
ETA has killed more than 825 people since the late 1960s in its campaign for an independent Basque country in northern Spain and south-western France.
The group declared a cease-fire in March 2006, but reverted to violence after failing to win concessions toward independence in negotiations with Mr Zapatero's government.