In Spain, a car bomb exploded Saturday in the commercial center of the Basque region's biggest city. Efficient police action avoided what could have been a massacre.

Large crowds were shopping in the center of Bilbao in the morning, taking advantage of the first Saturday of the annual post holiday sales, when an anonymous caller speaking in the name of the Basque separatist group ETA called the pro-independence newspaper Gara.

He said a car bomb had been parked in the city's main Gran Via thoroughfare, between two banks and near the seven-story El Corte Ingles department store.

The newspaper alerted police, who had barely half an hour to cordon off the area around a red automobile containing the bomb. It exploded at 1:45 and was estimated to have 15 to 20 kilograms of dynamite.

The blast shook the department store and surrounding buildings and was heard throughout the city, but police action prevented what could have been a massacre, and only a few people were slightly injured by flying glass.

Police said the car had been stolen at gunpoint earlier in the day in a nearby town. Its owner, who had been tied to a tree, was later found by police officers.

This was the first terrorist attack blamed on ETA since the center-right government of Spain's Prime Minister Jose Maria Aznar assumed the rotating presidency of the European Union. He has set the fight against terrorism at the top of the agenda for the next six months.

Saturday's blast would be the 31st car bomb to be set off by ETA since it called off a 14-month truce two years ago. Last year ETA claimed responsibility for killing 16 people in its campaign to carve out an independent Basque state in southern France and northern Spain.