A truck has ploughed into a crowded Christmas market in the German capital, killing 12 people, in what police suspect was a deliberate attack.
Local media, citing police at the scene, said first indications pointed to a deliberate attack on the market.
Berlin police said 12 people were killed in the crash. Forty-eight people have been taken to hospital with injuries.
Video footage from the scene showed stalls knocked over and people lying injured on the ground. Police cars and ambulances converged on the scene.
The incident occurred at Breitscheidplatz, near the fashionable Kurfuerstendamm avenue in the west of the city.
According to the DPA news agency, police believe the vehicle drove 50-80m through the market area.
A police spokesperson told German media the suspected driver had been arrested and another person, described variously as a passenger and a co-driver, had died in the crash.
The police have said the nationality of the suspected driver is unclear.
The truck belongs to a haulage company based in Poland and is registered in Gdansk, local media reports say.
The owner of the company told Polish radio his cousin had been driving to Berlin but he could not imagine his relative being responsible for the crash because he was a driver with 15 years' experience.
The truck careered into the market at what would have been one of its most crowded times, when adults and children would gather in the traditional cluster of wooden stalls that sell food and Christmas goods.
A witness, Emma Rushton, said the truck "ploughed through" the market and that people had been crushed.
"I heard a big noise and then I moved on the Christmas market and saw much chaos... many injured people," Jan Hollitzer, deputy editor in chief of Berliner Morgenpost, told CNN. "It was really traumatic."
German President Joachim Gauck said in a statement that it was an "awful evening for Berlin and for our country".
Berlin State Interior Minister Andreas Geisel said it was still not clear whether it was an accident or an attack.
But the White House on Monday condemned what it called an apparent "terrorist attack".
France said it would increase security at Christmas markets across the country immediately.
The truck crash in Germany comes five months after an attack in the French city of Nice when a 19-tonne truck was driven along the beach front, mowing down people who had gathered to watch the fireworks on Bastille Day.
The attack killed 86 people. Police shot dead the driver, Tunisian-born Mohamed Lahouaiej Bouhlel, at the scene.
The German truck incident occurred on the same day the Russian ambassador to Turkey was killed in a gun attack by a police officer, in Ankara.
Photo: AFP (An officer inspects the truck after it crashed into a crowd near a Christmas market in Berlin).