It was 11 in the morning. The sleek white Munich-Hamburg express, comprising 13 carriages and carrying between 350 and 400 passengers, was speeding along at 125 miles an hour, approaching the station in Eschede, 35 miles north of Hanover in northern Germany.
The train was more than four-fifths of the way towards its destination. The 600-mile journey normally takes five hours and 37 minutes.
Just before reaching the station at Eschede, the train approached a small bridge, about 30 metres wide, carrying a country road across the railway track.
There are two explanations for what happened as the train passed under that bridge.
One is that the Inter City Express jumped off the tracks after hitting a car, which had crashed through the railings on the bridge over the railway tracks and plunged on to the track, hitting the train.
A second explanation is that the train hit the bridge, and this made a car which had been parked on the bridge crash through the railings and fall on to the tracks.
A British eyewitness, Andrew Davidson, said that the first explanation coincided with what he had seen. He was stopped while approaching the bridge by the German police, who told him there had been an accident with a car coming off the bridge.
"The car was on its side on the tracks," he said. "Then, out of nowhere, came the express train and everyone just closed their eyes in disbelief. The train had no chance to stop. There was just an almighty great crash that seemed to go on for eternity."
Police confirmed that a car, which was the property of a railway employee working on track repair, had been found, crushed, beneath the wreckage. However, it was unclear where the car had been parked at the time of the accident.
An additional mystery was the extent to which a reported safety failing in the prestigious high-speed train was responsible for the accident.
According to the driver of the train, who survived the disaster, the locomotive became uncoupled from the carriages just before they jumped off the rails.
Klaus Rathert, a German regional official from Lower Saxony, confirmed reports to a news conference that the front locomotive had apparently decoupled from the passenger cars, saying this made them derail and crash into the bridge.
The train driver told officials he realised he had lost control over the passenger carriages when the train jerked and a brake signal came on.
One of the passengers, Wolf-Rudiger Schlibener, confirmed that two minutes before the accident he had heard "a tremendous rattling and shaking" in the train.
The locomotive cleared the bridge, but the 13 carriages behind the engine derailed and piled into each other. The force of the pile-up pushed some of the carriages several yards high into the air, like a concertina.
The impact brought the bridge crashing down on the last three carriages, killing many of the passengers who were trapped under tons of concrete.
Last night the German authorities had still not agreed absolutely on what happened. The interior ministry of Lower Saxony said it believed that a car did, in fact, fall over the side of the the overpass, derailing the train. But the German railway authorities were not able to confirm the cause of the disaster.Reuse content