“The incident will be investigated,” a spokesperson for the federal police said, adding that they planned to determine whether Deutsche Bahn errors were to blame.
“If evidence of wrongdoing arises, then preliminary proceedings will be opened with the state prosecutor's office,” the spokesperson said.
The incident occurred on Sunday in the Pulverdinger tunnel at Vaihingen am der Enz, near Stuttgart in the southern state of Baden-Württemberg. The train was travelling at a speed of some 200 kilometres per hour when there was an engine failure.
Between five and seven people suffered circulatory problems after the train stalled in the tunnel and technicians turned off the electricity due to safety concerns – which in turn shut down the train's climate control system.
Deutsche Bahn workers failed to pull the train out, and it was almost four hours before passengers were forced to change trains inside the tunnel to be transported to Stuttgart.
One passenger was taken to a nearby hospital. Meanwhile the Mannheim-Stuttgart line was closed in both directions.
So far none of the passengers has filed a criminal complaint, the police spokesperson added.
But Stefan Buhl, head of passenger advocacy organisation Pro Bahn, complained on Sunday that Deutsche Bahn had repeatedly failed to provide proper towing for broken-down trains or timely replacement trains.
“If Deutsche Bahn is already too overwhelmed to tow a train in such a situation, then it's hard to imagine what would happen in the case of a catastrophe,” he said.
Just last week 15 people were injured when an ICE crashed into a garbage truck in Lambrecht, in the western state of Rhineland-Palatinate. In July the company made headlines when a heat wave caused air conditioning meltdowns on some 50 trains.