In the Spanish capital of Madrid, more than 170 people were killed today after a series of bombs attacks at three train stations during morning rush hour. At least 500 people were also wounded The Spanish government has blamed the Basque separatist group ETA for the attacks but no group has taken responsibility. ETA — whose initials stand for Basque Homeland and Freedom — have fought for independence for the Basque region of northeastern Spain for decades. If the bombing was the work of the ETA it marks by far the group’s largest attack. In 1987 a bombing at a supermarket in the Basque country killed 21 people. But a prominent Basque party leader that has been linked to ETA said the group was not behind the attacks. He suggested the “Arab resistance” may have carried out the attacks. The Basque official noted that ETA usually phones in warnings. There were no warnings before today’s attack. The bombings came three days before Spain’s elections on Sunday. The country’s political parties have suspended campaign for the elections. A government spokesperson described the bombings as an attack on Spanish democracy. The government has also declared three days of mourning. The Washington Post reports the attacks marks one of the largest terror attacks in Europe since the end of World War II.