From typicallyspanish.com

National
No injuries as ETA set another bomb in the Basque Country
By h.b.
Apr 20, 2008 - 8:53 AM

A bomb placed by Basque terrorist group ETA exploded at 0325 this morning outside the Casa del Pueblo, the Socialist Party offices in Elgoibar, Guipúzcoa. There were no injuries despite the fact that the device went off five minutes ahead of the time given in a telephone warning at 0232 to the DYA road breakdown service. However a large amount of material damage was done to surrounding buildings and cars.
The offices were being reformed, having already undergone a half dozen or so attacks.

It comes just over 48 hours after the attack on Socialist party offices in the La Peña district of Bilbao. We now know that device was made up of five kilos of explosives, and slightly injured seven regional police offices.