People hold banners that read "No to ETA" as they observe a moment of silence for the killing of two police oficers, outside Madrid´s town hall July 31, 2009. A bomb placed under a police car killed two officers on the Spanish holiday island of Mallorca on Thursday, in what authorities called the second major attack by the Basque separatist rebel group ETA in two days. REUTERS/Susana Vera (SPAIN CONFLICT POLITICS)