German security forces work at the site of an accident at a Christmas market on Breitscheidplatz square near the fashionable Kurfuerstendamm avenue in the west of Berlin, Germany, December 19, 2016
VON PRESS Europe: Interior Minister Thomas de Maiziere said the circumstances of the crash were still unclear, adding: "I don't want to use the word 'attack' yet although a lot points to that."
Police said on Twitter that they had taken one suspect into custody and that another passenger from the truck had died as it crashed into people gathered around wooden huts serving mulled wine and sausages at the foot of the Kaiser Wilhelm memorial church in the heart of former West Berlin.
The nationality of the suspected driver, who fled the crash scene and was later arrested, was unclear, police said.
German media cited local security sources as saying that there was evidence suggesting the arrested suspect was from Afghanistan or Pakistan and entered Germany in February as a refugee.
"We heard a loud bang," Emma Rushton, a tourist, told CNN. "We started to see the top of an articulated truck, a lorry ... just crashing through the stalls, through people."
Rushton said the truck seemed to be traveling at about 40 mph (65 kph).
Police later said that 48 injured people were brought to Berlin hospitals.
The incident took place near a famous Berlin landmark - the Gedaechtniskirche or memorial church built in 1891-95, which was left a ruin with a jagged tower after it was damaged in World War Two bombing raids as a monument to peace and reconciliation.
Berlin police said on Twitter they were investigating leads that the truck had been stolen from a construction site in Poland.
German officials have said the country, which accepted nearly 900,000 migrants last year, many from the war-torn Middle East, lies in the "crosshairs of terrorism."