A powerful car bomb exploded early Wednesday in northern Spain outside a barracks housing police officers and their families, slightly injuring 46 people and causing major damage in the area. The attack was blamed on Basque separatist group ETA. Most of the injuries from the blast in Burgos were from flying glass, and 38 of the wounded were treated in hospitals, regional ministry representative Miguel Alejo said. Many of the injured were Civil Guard police officers and family members. The bomb detonated around 4:00 a.m. (0200 GMT, 10 p.m. EDT Tuesday) and left a crater that had filled with water from broken underground pipes, Alejo said. "The car used to cause the explosion has been displaced some 70 meters (230 feet) so that gives you an idea of the power of the blast," he said. Police and emergency services did not receive any warning that a bomb had been planted, but the explosion had the hallmarks of an ETA attack, Alejo said. It was not immediately clear how many people were in the building at the time. ETA, which has killed more than 825 people since it launched a campaign in 1968 for an independent homeland in Basque region of northern Spain, typically phones in warnings that a bomb is about to explode giving time to authorities to evacuate the area. The last attack blamed on the group was July 10 when a bomb exploded outside an office of the Spanish prime minister's party in the Basque town of Durango, causing significant damage but no injuries. The group's last fatal attack took place June 19, when a bomb attached to the underside of a car killed a Spanish police detective whose job was to investigate ETA. Television images Wednesday showed considerable damage to a 14-story barracks building in Burgos and many residential dwellings around it with windows and some walls blown in by the power of the explosion. It is common for members of the paramilitary Civil Guard police force to live in barracks with their spouses and children. The force is chiefly in charge of policing rural areas and guarding official buildings. In an attack on May 14, 2008, ETA killed a Civil Guard officer in a car bombing outside a barracks in the Basque town of Legutiano. There were 29 people in the building at the time. Burgos is an important regional capital and contains a historic city center with important tourist attractions. ETA, whose name is a Basque-language acronym for Basque Homeland and Freedom, had declared what it called a permanent cease-fire in 2006, but reverted to violence within months after peace talks with the Spanish government went nowhere. Dozens of alleged members of the organization have been arrested in recent years in Spain and France including several of its supposed leaders.