Nine people have been killed and at least 50 people have been injured after a semi-trailer crashed into stalls and shoppers at the market near Breitscheidplatz in central Berlin.
Jan Hollitzer, the deputy editor-in-chief of the Berliner Morgenpost, told the BBC he was walking on the other side of the road when the truck crashed into the market.
"I heard a loud noise from the houses that were destroyed by the truck and I heard screams," he said.
"It's like the pictures we saw from Nice ... I saw the broken house and I saw many destroyed glass on the ground and some fluid - I don't know what it could be, it could be red wine or it could be blood, I don't really know - and I saw some people lying on the ground and also some people under the truck.
"That's what's really horrible. And it was chaotic, as you can imagine."
Former Brisbane resident Trisha O'Neill told the she had been at the markets when truck crashed into the stalls.
"We sat just behind the stall having a gluhwein and then all of a sudden there was a big boom and the people in front me jumped on top of me," she said.
"I just saw this huge black truck speeding through the markets crushing so many people and then all the lights went out and everything was destroyed.
"I could hear screaming and then we all froze. Then suddenly people started to move and lift all the wreckage off people, trying to help whoever was there."
Ms O'Neill told the ABC she was afraid to see the resulting carnage, but she saw "blood and bodies everywhere".
"People, including children and older people, weren't moving — people were crying and I just burst into tears," she said.
"All the police and ambulance came and we decided to walk away from the streets and go somewhere safe."
The reported "there was a ghostly silence in the square" following the alleged attack.
"The people were hurting in front of the stalls, holding each other in their arms, others clasping their hands in front of their faces, others still crying and hugging each other," they reported.
Julian Reichelt, editor in chief of Bild Berlin, said that there was currently a massive security operation underway.
"The scene certainly looks like a reminder of what we have seen in Nice," Reichelt said.
The Berlin police have used Twitter to urge people to stay away from the scene, to keep the streets clear and not to spread rumours before the facts are known.
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