Barcelona horror: 'Absolute terror etched on their faces' - Aussie tourist

Injured people are treated in Barcelona, Spain. Photo / AP

An Australian tourist has told of the horror that unfolded moments after a van ploughed into crowds in the Spanish city of Barcelona, killing at least 12 people in a terrorist attack.

Susan McLean was about 100m from the scene as the van zigzagged down one of the city's busiest avenues, mowing down pedestrians and leaving bodies strewn across the ground.

"All of a sudden there was this tidal wave of people running from both Placa de Catalunya and Las Ramblas towards us screaming, crying and with absolute terror etched on their faces," she told Nine Network on Friday.

"Initially we couldn't hear anything other than all these people running towards us. Several of them were calling 'gun, gun', so first of all we thought someone had been shot.

"Then they just kept sort of - it was all in Spanish. It was very difficult to understand but they were sort of pushing us into shops."

Image 1 of 12: Police officers stand next to the van involved on an attack in Las Ramblas in Barcelona, Spain. Photo / AP

McLean, who was separated from her husband in the panic, said the scene reminded her of Melbourne's January 20 Bourke Street Mall killings, when a man in a car mowed down pedestrians. Six died and up to 30 were injured.

"That was quite scary because I wasn't sure where he was but the shopkeepers were great. They pulled everyone inside and put the shutters down.

"My first reaction was the Bourke Street massacre, because that is what it reminded me of, the vision of people fleeing in just such terror."

Melbourne holiday-maker Julia Monaco told Nine police on the scene suddenly ordered her and her family inside a shop just across from Las Ramblas as the attack happened.

"In a split second it all kind of changed and everyone just started running and panicking and running for their lives and crying and screaming and we were forced back into the store, told to get away from the windows and to get low on the ground.

"We were huddled at the very back of the store lying flat on if floor and were in that position for about 20 minutes with no real understanding of what was happening other than it was incredibly serious."

- AAP