The bodies of the three suspects, reportedly of north African origin, were buried beneath the rubble of the partly-destroyed four-story building, he said. He said the men “had caused (the blast) with the aid of a strong explosive”. It was possible a fourth person had “triggered the explosion”, then left the area before it was cordoned off by police, the minister said in translated remarks from a live televised press conference. Thick grey smoke billowed over the building wreckage, while a police helicopter shone a spotlight down on the scene. Ambulances were on site and emergency medical stations had been set up. Earlier, Acebes confirmed that a bomb found yesterday on a train track in Spain had used the same kind of explosive – Goma 2 Eco – as that used in the March 11 attacks, in which more than 1900 were also wounded. Acebes said the army, police and Renfe were operating a permanent surveillance system across Spain. Meanwhile, judicial officials freed four suspects arrested earlier in connection with the March 11 attacks, leaving a total of 15 suspects now facing charges, with a further five still under questioning. 
Police trawl through the wrecked building.
Another 11 police officers were wounded in the blast, which went off when security forces tried to enter an apartment building in a Madrid suburb where the suspects were holed up, Interior Minister Angel Acebes said.
