Two trains collided head-on in the southern German state of Bavaria on Tuesday morning.
At least 10 people have died, while 17 others were seriously injured.
Local media say a wrong decision made by a dispatcher could be the cause for the accident.
A railway worker manually disactivated the automatic signalling system to let the first train, which was running late, go past.
It then crashed into a second train, which was forging ahead on the same track in the opposite direction.
Due to a curve in the track, the drivers had no visibility before the collision, which caused several compartments to derail.
About 150 people were onboard the two trains. Rescuers are still searching for one person that remains missing.