At least 13 people have died after a coach carrying Polish tourists crashed near Berlin, German police say.
The bus came off the A10 motorway at Schoenefelder Kreuz, about 30km (20 miles) from Berlin.
Nineteen people were severely injured, while 20 others were less badly hurt in the crash on Sunday morning.
Initial investigations indicated that the bus had been forced off the road by a car joining the motorway, a police spokesman said.
The driver of the car is said to be among the injured.
Poland's Prime Minister Donald Tusk and Health Minister Ewa Kopacz travelled in Berlin to view the crash site and to visit the injured.
Mr Tusk appeared shaken when he made a brief statement at a Berlin hospital.
"All I can say is many thanks for your efforts, your help," he said.
Ahead of his arrival, Germany's Chancellor Angela Merkel called Mr Tusk to express her sympathy. They met later at the Polish embassy in Berlin.
German Foreign Minister Guido Westerwelle said in a statement: "This accident affects not only our Polish friends, but us as well."
Earlier, police spokesman Jens Quitschke said it appeared that the driver of the car lost control while joining the A10.
"They collided with a Polish travel coach on the way back home from Spain. The bus driver also lost control and crashed into (a) bridge support."
Police and fire crews - about 250 in number - were despatched from Berlin and the surrounding region.
Helicopters lifted the most seriously injured to hospital, while the rest were treated at the scene in tents put up by emergency services.
The bus was returning to Poland from a holiday tour of Spain.
German officials are setting up an information point for the Polish relatives of the victims.