A white Fiat van was used to carry out the attack on Las Ramblas, a street of stalls and shops in central Barcelona that is one of the city's top tourist destinations.
The attack started at the northern end of the tree-lined promenade at around 5pm local time.
The vehicle travelled more than a third of a mile down Las Ramblas, striking pedestrians as it went.
The damaged vehicle came to a halt and police were on the scene quickly, later confirming it was a terror attack.
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