When I arrived at Atocha station minutes after the bomb attacks, hundreds of people were crowding around police cordons trying to get a sense of what was going on.
By Danny Wood
BBC correspondent at Atocha station
The explosives were placed on crowded commuter trains
Most were standing around stunned.
It was minutes after the bomb blasts and I'd rushed down to the scene from my nearby apartment.
The site of the explosions down on the railtracks was about 100m from the police cordon.
Dozens of ambulances were screaming to and from the scene.
I saw a number of people crying in the street.
The choking rush hour traffic was at a virtual standstill as police cleared a wide area, redirecting traffic and people in the station locality.
Large numbers of police and emergency workers had arrived at the scene very quickly.
One construction worker told me he was having coffee in the centre of Atocha train station when he heard the first explosion, then a few minutes later two more.
He described seeing large plumes of smoke, bloodied survivors emerging from the station platforms and then scenes of complete chaos as hundreds of people ran in panic, from one of Madrid's largest and busiest stations.
Near the roundabout adjacent to the station, a man who works in the Carlos V delicatessen broke down into tears as he told me how horrified and shocked he was by the attack.
On the street, the locals appear in no doubt that these attacks are the work of the armed Basque separatist group Eta.
Television and radio here is devoting round the clock coverage to the events. One commentator described today as Spain's twin towers attack.
Next door in cafes and restaurants that line Atocha street, locals crowded in to watch events unfold on television.
Most sat in stunned silence.
Hours later ambulance sirens could still be heard taking scores of injured to hospital.