The incident at Kaiser Wilhelm Memorial Church on Monday night, which officers suspect was a terrorist attack, also left nearly 50 people hurt, some seriously.
On Twitter, they said: "Our investigators are working on the assumption that the truck was intentionally driven into the crowd at the Christmas market on Breitscheidplatz.
"All police measures concerning the suspected terror attack at Breitscheidplatz are being taken with great speed and the necessary care."
Worship pastor at Berlin International Community Church, Andrew Mack told Premier's Inspirational Breakfast people are "very disturbed and devastated" to believe such an incident could unfold in Berlin.
Explaining that he was at a choir practise near the scene on Monday evening, he said: "One of the members had something pop-up on their phone and they just said there's been a [vehicle] that ran into the market and they're not sure what it is but people have been killed.
"So, we all just stopped right then and started to pray."
The US State Department warned less than a month ago extremist groups were focusing "on the upcoming holiday season and associated events" and it urged people to take care at markets and other public places across Europe.
The incident echoes the Bastille Day lorry crash in the French city of Nice - which Islamic State claimed responsibility for - on 14th July which killed 86 people.
The owner of the Polish-registered truck feared the vehicle may have been hijacked, while police confirmed a Polish national passenger in the truck was among the dead.
A suspect, thought to be the driver, was stopped around 1.5 miles away and he was being interrogated, a Berlin police spokesman said.
Andrew Mack from Berlin International Community Church went on to say that he hoped all different types of churches in the German capital "would shine the light of Jesus."
Speaking about how the churchs' senior pastor, Steve Mack, led prayers on Facebook Live on Monday, he added: "He did a prayer for those affected in Berlin.
"[It was] just a declaration of God's blessing over the city of Berlin and protection for the law enforcement and government as they work through what they need to work through to just continue to protect the German people."