The city of Barcelona has been thrown into mourning.
The families of 13 people are grieving after a driver deliberately slammed a van into them.
The attack, the latest in a wave of vehicle rammings across Europe in recent years, caused panic on the streets of Spain’s largest city and drew condemnation from world leaders.
“We can confirm there are 13 dead and more than 50 injured,” regional interior minister Joaquim Forn said in a tweet.
Catalan police said they had arrested one suspect, and denied earlier reports that the perpetrator was holed up in a bar near the scene.
The famous Las Ramblas is one of Barcelona’s busiest streets, lined with shops, restaurants and normally thronged with tourists and street performers until well into the night.
Police said there had been a “huge collision” between a van and pedestrians on the thoroughfare and a police source said officers were seeking a total of two suspects.
Spain’s royal family condemned the assault in unusually strong terms, vowing that their country would not be “terrorised” by extremists.