BERLIN — At least four people were killed and about 30 injured when a train derailed in Germany's south-eastern state of Bavaria, police said.

The train, which was carrying many students, was heading to Munich when three carriages came off the tracks near Garmisch-Partenkirchen.

Investigators say they are working to establish what caused the accident.

Chancellor Olaf Scholz expressed shock at the incident and said his sympathy was with families of the victims.

An official from the Garmisch-Partenkirchen local authority had initially suggested that some 60 people had been injured.

But Stefan Sonntag, a spokesperson for the German federal police, said that figure referred to the number of passengers on the train.

The accident happened at around 13:15 local time (11:15 GMT) on Friday, shortly after the train left Garmisch-Partenkirchen for Munich.

Sonntag told reporters that 15 of the injured were in serious condition at a local hospital. Authorities also confirmed that a number of children were among those hurt.

It is unclear what caused the accident, which occurred as the train rounded a wide bend, but Bavaria's Transport Minister Christian Bernreiter told regional broadcaster BR that the accident might have been the result of a technical fault.

"There were no third parties involved here, so one must assume that some technical reason — either on the vehicle or on the rail — was the cause," he said.

Emergency workers had to use ladders to climb down through windows to reach survivors trapped in upended carriages and officials said that people had been "pulled through the windows" to rescue them from the wreckage.

Six helicopters, including three scrambled from the Austrian region of Tyrol, were sent to the scene to assist in rescue efforts.

The area has started preparations to host the G7 summit of world leaders later this month and a number of police and soldiers deployed to the region were enlisted as part of the rescue operation.

A US soldier based at a nearby air base was driving past when the train derailed. He told local media the accident had been "just awful — suddenly the train overturned".

The accident comes as Germany launched a new discounted rail ticket and Sonntag said the regional train was "very crowded and many people were using it, hence the high number of injured".

Part of the route between Munich and Garmisch-Partenkirchen has been blocked off and traffic has been diverted, German rail operator Deutsche Bahn says.

Germany's deadliest rail crash in modern times occurred in 1998 when a high-speed train derailed in Eschede in Lower Saxony, killing 101 people.

The country's most recent fatal crash took place in February, when one person was killed and 14 others were injured in a collision between two trains near Munich.

In a separate development, a carriage on an Italian high-speed train traveling from Turin to Rome derailed while approaching the capital.

Local emergency officials say nobody was injured in the incident, which saw the train's back carriage come off the tracks as it neared the Serenissima tunnel in Rome. — BBC