A manhunt was underway after a van ploughed into Barcelona's busiest tourist street, Las Ramblas, in what police are calling a terrorist attack.
Catalan police say they have arrested one man linked to the Barcelona van attack but were continuing to search for other suspects.
The van drove for around 500 metres before it came to a stop. Police were searching for at least one person.
The police said that 13 people were killed and at least 50 injured, 10 of whom were in a serious condition. They also confirmed that it was a terrorist attack.
Hundreds of people were stuck in shops, bars and homes as police searched the area amid conflicting reports of hostages, shoot outs and secondary vehicles.
Las Ramblas is a wide boulevard with a central walkway as well as two pavements at the side of the road. It is full of terrace cafes, restaurants and hotels.
A spokesman for the first minister of Barcelona, Artur Mas, tweeted an image of Catalan flag superimposed with a black ribbon and the slogan: "We are stronger and we will win because our values are stronger and are winners. Stay strong Barcelona, visca Catalunya!"
UK Prime Minister Theresa May, French President Emmanuel Macron and President of the European Council Donald Tusk offered their sympathy and support to the people of Barcelona.
No group has claimed responsibility so far. Websites connected to ISIS celebrated the Barcelona attack but no official site claimed responsibility.
The latest crash follows terrorist attacks with vehicles in France, Germany and the UK.
In London in June, a speeding van hit pedestrians on London Bridge before assailants attacked people in cafes and restaurants in Borough Market, killing 8 people.
In March, a lone attacker ploughed a car into pedestrians on Westminster Bridge in London, killing four and injuring over 50, before crashing into the fence surrounding the Houses of Parliament and stabbing a police officer to death before being shot and killed by police.
In December, a Tunisian man drove a stolen truck through a crowded Christmas market in Berlin, killing 11 people. The terrorist had previously killed the truck driver.
Also last year, in a similar attack in Nice, in the south of France, on July 14, 2016, a Tunisian-born French citizen killed 84 people by driving a rented truck into a crowd of revelers celebrating Bastille Day, France's national day.
