A car bomb blamed on the Basque separatist group ETA exploded in northern Spain on Sunday morning, injuring several people and causing heavy damage, officials said.
The explosion near government offices in the city of Logrono tore through five floors of an apartment building, trapping about a dozen people inside for hours until firefighters could free them.
An anonymous caller claiming to speak on behalf of ETA alerted authorities to the bomb about 45 minutes before it went off, police said.
The attack in Spain's Rioja region, about 155 miles north of Madrid, came just two days before President Bush is due to visit the Spanish capital at the start of a European tour.
ETA, which has mostly targeted low-ranking Spanish politicians, businessmen and journalists since calling off a 14-month cease-fire in late 1999, has tended to keep a low profile during major international events in Spain.
Spanish officials said no "extraordinary" measures were being taken for the one-day presidential visit, but security was expected to be tight.