The devastating terror attacks in Madrid saw 10 bombs explode on four trains in three stations during the busy morning rush hour.
Each of the trains was laden with commuters; office workers, students and schoolchildren.
Four bombs exploded on a train just outside Atocha station
Three of the trains set off from Alcala de Henares, about 12km to the east of Madrid. The fourth originated from Guadalajara, but passed through the station en route for the city.
Police later discovered a stolen van containing seven detonators and an Arabic language tape near the station.
All of the trains left Alcala de Henares within 15 minutes of each other, from 0600GMT onwards.
As each train passed through the station, investigators say, the bombers loaded rucksacks each containing about 10 kg (22 lb) of explosives onboard.
At 0639, as the first train drew to a halt inside Atocha station, three bombs exploded in the third, fourth and sixth carriages. At least 34 people were killed and scores wounded.
Almost simultaneously, four bombs detonated in the first, fourth and sixth carriages of the second train about 500m outside the station. At least 59 people were killed and scores wounded.
This train was running two minutes late.
Investigators believe the bombers intended to set the bombs off on both trains inside the station simultaneously to maximise their power and cause severe damage to the building.
Emergency services set up an temporary hospital at a sports centre on Tellez street close to Atocha station to deal with hundreds of injured people.
Police also carried out controlled explosions on three other unexploded devices found at the station.
At 0641, two bombs went off in the fourth and fifth carriages of the third train as it passed through El Pozo station, back down the line from Atocha. At least 70 people were killed and many more wounded.
At about 0642, the fourth train was passing through Santa Eugenia station when a bomb exploded in the fourth carriage, killing at least 17 people and wounding dozens.
Each device was detonated by mobile phone, investigators believe.
At each station, emergency services set up temporary hospitals to treat the injured. More serious casualties were ferried to hospital by helicopter.
At 0840 the Spanish Red Cross put out an urgent appeal for blood amid dwindling supplies.
The Interior Ministry warned motorists to stay off the capital's roads to allow the swift transfer of the wounded to hospital.
By 0927 all incoming trains were stopped due to fears of further explosions.
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