WARNING: Graphic content
A GRAPHIC video of aftermath of the Barcelona terror attack has been posted online showing bloodied bodies strewn across the pavement.
The 19-second clip, shared on Twitter, shows the lifeless bodies of six people lying on the ground, some in pools of blood.
Horrified onlookers can be seen running for their lives as sirens blare in the background.
Paramedics are caught on the video tending to the injured, including what appears to be a young child.
The shocking vision shows people tending to bodies on the pavement.
Up to 13 people are dead and another 80 were injured when a white van ploughed into crowds at the busy tourist strip Las Ramblas in the heart of Barcelona, Spain, on Thursday afternoon.
Local police are treating the incident as a terrorist attack.
Eyewitness videos show people tending to injured people in the pedestrian mall.
Other videos posted online show crowds running for their lives in the aftermath of the attack.
"I was in Calle Hospital when I saw people coming from Las Ramblas running and shouting. I didn't know what was happening so I ran too," Nats Sisma Villaluna wrote alongside a video he posted on Facebook.
"This is sad and scary."
Witnesses have told CNN that the van appeared to deliberately "zigzag" along the pedestrian mall, presumably to inflict maximum damage to the people.
An unidentified witness told Spanish station TV3 there was "a hell of blood".
Police have arrested two suspects who they are "treating as terrorists".
Australian woman Susan Maclean, who is on holiday in Barcelona with her husband, said she was "very lucky" to have avoided the van as it ploughed through the crowds.
"All of a sudden, there was this screaming and hordes of people, like a tidal wave of people, fear etched in their faces, running towards us, many of them yelling in Spanish," she told Channel 4 News.
"We had no idea what was going on. My first thought was this is a terrorist attack."
Ms Maclean said she felt "unbridled fear" during the incident as she was barricaded into a nearby shop for safety.
"It was very difficult to know what was going on," she said.
"People were shouting. We could hear the word 'shooting, shooting'. We weren't really sure whether that was shooting as in the English or a Spanish word so it was just unbridled fear."
Witness Ethan Spibey told Sky there was "chaos" in the aftermath of the attack.
"People just started running and screaming," he said.
"There was loud bangs and people just started running into shops.
"There was a mini stampede where we were down one of the alleyways."
Las Ramblas is a popular spot for tourists thanks to its wide pedestrian areas, shops, bars and restaurants. All businesses in the area have now been evacuated as police investigate the incident.
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