"Everything we see here indicates that we are dealing with an Islamist terrorist attack," Interior Minister Alexander Dobrindt told reporters at the scene, where he said the van drove down a pavement, running over pedestrians.
The attack happened in the Tiergarten park near the Brandenburg Gate about 10pm, not far from one of Europe's biggest annual LGBTQ Pride celebrations, Christopher Street Day.
The suspected perpetrator had "attracted attention in the past through a high number of criminal offences, through radicalisation, through membership of the Islamist scene," Dobrindt said, adding that he was a German citizen with a Lebanese background, born in Germany in 2005.
Berlin mayor Kai Wegner, standing next to Dobrindt, said the incident was "probably an Islamist terrorist attack on our way of living alongside one another, on our liberal democracy, our openness and our freedom".
German Chancellor Friedrich Merz called on people not to be intimidated and divided by the attack on Berlin's Pride parade.
Such criminals and extremists have no place at the heart of our society, Merz said in Berlin shortly before a memorial service on Sunday.
"We are more, we are stronger," he said.
"These acts have only one purpose: they want to divide our society, they want to take from us the most important thing we have - namely our openness and our freedom," Merz said.
Berlin police identified the suspect as Abdul B, 21, and published his picture, asking the public for information on his whereabouts.
They described him as slim, about 1.90 metres tall, with black hair, and last seen wearing a black hooded top and white trousers.
But they also warned the public not to approach him, saying he was "possibly armed and dangerous".
Security sources told Reuters the suspect had been released from juvenile detention only two months ago.
They said he was known to domestic intelligence and was among the hundreds of people classed as potentially dangerous, a label that usually leads to scrutiny or monitoring.
After mowing people down with the vehicle, the attacker injured some with a bladed weapon, thought to have been a machete, Dobrindt said.
The fire service said overnight that three of the injured were in a life-threatening condition.
It was unclear whether the perpetrator had acted alone, since police said more than one person may have got out of the van.
Reuters TV footage from the scene on Sunday morning showed a white mini-van crumpled into a tree.
The mass-circulation newspaper Bild said it was a delivery vehicle that Abdul B had rented.
German media reported that police had searched the suspect's Berlin apartment.
Hundreds of people gathered at Berlin's Brandenburg Gate on Sunday to mourn the victims of the attack.
The attack comes at a sensitive time for conservative Chancellor Merz's unpopular coalition government, which is going through a bruising cabinet reshuffle as critics accuse it of being ineffective.
State elections take place in two months, with the nationalist populist opposition party Alternative for Germany (AfD) campaigning on issues including immigration and security in a bid to secure control of a regional government for the first time.
The AfD was quick to comment on the attack.
"We will not allow religious extremists to divide our country with violence and intolerance!" AfD co-chief Tino Chrupalla said on X.
Germany has been the site of a series of vehicle attacks on crowds in recent years.
with DPA
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