The Scottish-American actor, who starred in Doctor Who and Torchwood, was near the scene in Berlin after several people were injured after a vehicle drove into pedestrians in Berlin, according to German authorities.
The Dancing on Ice star wrote on social media: “We think we have witnessed a terrorist attack here in Berlin we’re not sure there’s a lot of people dead bodies all over the place we’ve seen a car that came down the road and ended up in a storefront covering three city blocks it’s pretty horrific.”
He said he heard a “bang and a crash” when he was in a store, and came out to see “carnage”
In an interview with the BBC he said: “After we heard a noise, we were in a store that was across from the final point of the car going into the store front.
“We saw a car that had careened through a cafe area and into a store front window and we walked around thinking it was just a car accident. We saw that the person in the car had been pulled out, and there was another person on the ground.
“We turned and started walking down the street and it wasn’t until we got midway down the street that we saw the dead body in the middle of the road and we kept walking and the police then flew into the area.
Speaking about the scene a little further down the road, the actor said: “There was multiple people on the ground and I am sure that’s where the life threatening injuries happened because I saw someone being resuscitated, I saw someone being literally thrown onto a stretcher and put into an ambulance.
"There was multiple bodies on the ground there, some people getting up and limping away - it was like a two city bloc and you could see where the car had came onto the pavement, barrelled through people and then gone onto the street where it hit the person on the road and killed them, then barrelled back onto the pavement and went into the store front after going through the cafe area.
“Next to the person who had passed away there was one of those bollards that had exploded because the car had careened right through it. It clearly didn’t do any difference or help”
When pressed that the incident was not yet declared as a terrorist incident, or an accident, Barrowman said: “I hate to say this, but from an eyewitness point of view, and I understand you have to go by what police say, we were there and if the person had passed out at the wheel they would have stopped much sooner.
"This person was terrorising people by driving up on the pavement and on the road so no matter what the emergency services say or don’t say, we witnessed a terrorising activity that was to the general public, and it was deliberate.”
His husband Scott Gill who was also interviewed by the BBC said: “There was no sense of fear and panic, but when we walked up we could see more debris on the road.”
At least one person was killed and eight others injured after a vehicle drove into pedestrians in Berlin, rescue services said.
Berlin fire service spokesman Stefan Salzwedel, who confirmed the casualty figures, was not immediately able to provide further information on the victims.
Large numbers of rescue vehicles and first responders were at the scene