The head-on collision of two commuter trains in southern Germany that left 10 people dead and dozens injured was caused by "human error," a source close to the investigation told dpa of the initial findings.
Who was exactly responsible for the crash was not immediately known.
Eighteen people were seriously injured and another 63 sustained light wounds, police said.
One missing person was believed to still be among the wreckage. Police said there was little chance of their survival.
The accident, which occurred near the Bavarian town of Bad Aibling at 6:50 am (0550 GMT), saw two commuter trains carrying a total of 150 people collide at full speed on a single-track line in a partially wooded area.
Due to a curve in the track, the drivers had no visibility before the two trains crashed into one another, causing several compartments to derail, Transport Minister Alexander Dobrindt said in a press conference.
Prosecutors had said earlier that they were investigating the possibility of human error and of a technical fault.
One focus had been the system that causes trains to brake automatically when they are on the wrong track to prevent such head-on collisions.
A spokesman for rail operator Deutsche Bahn said the system was enabled at the time of the accident and had been tested about a week ago.
"It was frightening to see how the two trains drilled into one another - the second train was completely torn apart," Dobrindt said, adding that he was in close contact with Chancellor Angela Merkel and Bavarian premier Horst Seehofer, who had both expressed their condolences to the victims' relatives.
As part of the rescue effort, as many as 15 helicopters transported people with serious injuries to nearby hospitals and were seen lifting victims to the opposite side of the river in body bags. Those with less severe injuries were being treated at the scene.
Federal and state police, paramedics, the fire department, the lifeguard service and the Red Cross had formed a rescue operation comprising more than 500 people.
A spokesman for the team of paramedics working at the scene said that favourable weather conditions, the time of day and the fact that it is a holiday in Bavaria had helped to minimize losses in the accident.
Two black boxes from the trains were being examined for information about the reason for the collision. A third was still missing in the wreckage.
Deutsche Bahn said that two cranes had been ordered to remove the wreckage beginning Wednesday and that the effort would take several days.