Hundreds of people are pausing at a make shift memorial in Berlin near the site of Monday's attack that killed 12 and injured at least 50.
Berlin police have reportedly stormed disused Tempelhof Airport which has been turned into a refugee camp in the wake of the Christmas market attack that killed 12 and injured up to 50 people.
An elite unit of armed police raided the airport this morning, according to media reports. The site wasclosed years ago and has been converted to temporary accommodation for refugees.
It's believed police entered the site around 4am.
Berlin police have claimed the truck attack was deliberate and said they are working at "full steam" to find those behind it.
"Our investigators assume that the truck was deliberately steered into the crowd at the Christmas market at Breitscheidplatz," police said on Twitter.
"All police measures related to the suspected terrorist attack at Breitscheidplatz are progressing at full steam and with the necessary diligence," police said.
Meanwhile, it's believed the truck attack on a Christmas market in Berlin that killed 12 and injured 48 was a deliberate act of terrorism, with the driver identified as a young Pakistani migrant.
Bild newspaper cited security sources as saying the suspect, who was arrested soon after the attack, is a 23-year-old from Pakistan named "Naved B".
In legal cases German officials routinely issue an initial for the surname rather than the full name.
Firefighters look at the debris. Photo / AP
Local broadcaster rbb cited security sources as saying the arrested truck driver came to Germany via Passau, a city on the Austrian border, on December 31, 2015.
It cited the sources as saying the man was born on January 1, 1993 in Pakistan and was already known to police for minor offences.
German newspaper Die Welt said police special forces stormed a hangar at Berlin's defunct Tempelhof airport housing a refugee accommodation centre at around 4am on Tuesday.
It said, without citing its sources, the arrested man was registered there.
Prosecutors declined to immediately comment on the report.
Police said a Polish man was found dead in the truck owned by a Polish company but added he was not in control of the vehicle.
The trailer of a truck stands beside destroyed Christmas market huts. Photo / AP
According to German press agency DPA, the company's owner, Ariel Zurawski, told Polish broadcaster TVN 24 that the truck had earlier in the day been driven by his cousin, who had been transporting steel to Berlin and had not been reachable since the late afternoon. He said he was sure his cousin was not an attacker.
"It can't have been my driver," he said. "Something must have happened to him ... I am so shocked."
German police said later they were working on the assumption that the truck had been stolen from a construction site in Poland.
The truck crashed into people gathered on Monday evening around wooden huts serving mulled wine and sausages at the foot of the Kaiser Wilhelm memorial church - left as a ruin after WWII - in the heart of former West Berlin.
On Tuesday morning, the black truck was still visible at the site of the incident and a few candles and roses had been laid by the entrance to a nearby station.
Flowers are placed near the Kaiser Wilhelm Memorial Church in Berlin. Photo / AP
Flowers were being laid in the centre of the nearby Kurfuerstendamm, a prestigious shopping street. One woman was crying as she stopped by the flowers.
Amateur videos taken directly after the attack and aired on several German broadcasters showed injured people lying on the ground against the backdrop of police sirens.
"We are mourning the dead and hope the many people injured can get help," German Chancellor Angela Merkel's spokesman Steffen Seibert said on Twitter.
Justice Minister Heiko Maas said on Twitter that the federal prosecutor had launched preliminary proceedings into the incident.
Media people stand near a truck which ran into a crowded Christmas market. Photo / AP
If the suspect is proven to be a migrant, it could further sour sentiment towards asylum seekers in Germany, where more than a million people fleeing conflict and poverty in the Middle East, Africa and elsewhere have arrived this year and last.
The record influx has hit Chancellor Angela Merkel's popularity ratings and boosted support for the anti-immigrant Alternative for Germany (AfD). Senior AfD member Marcus Pretzell blamed Merkel for the attack on Twitter.
Manfred Weber, head of the centre-right European People's Party, said: "It's not an attack on a country; it's an attack on our way of life, on the free society in which we are allowed to live."
Flags will be hung at half-mast around Germany on Tuesday.
