At least 13 people have been killed and 100 have been injured after a van mounted a pavement and ploughed into pedestrians at a popular tourist spot in Barcelona.

Here is everything we know about the attack so far:

What happened?

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.

Eyewitnesses described scenes of widespread panic, with crowds running in waves away from the area.

The damaged vehicle came to a halt and police were on the scene quickly, later confirming it was a terror attack.

The victims:

At least 13 people have been killed and 100 have been injured.

Fifteen of those injured are in a serious condition and Catalonia's regional interior chief Joaquim Forn said that the number of dead is likely to rise.

The identities of the victims have not yet been confirmed.

A Belgian national is among the dead, Belgium's deputy prime minister Didier Reynders confirmed on Twitter.

Who is behind the attack?

Two suspects are in custody and are being treated "as terrorists", Catalan Police have confirmed.

The suspects being detained are reportedly a Spanish national from Melilla and a Moroccan, but neither of them is believed to have been the driver of the van.

Local media have named Driss Oukabir, 28, as the man suspected of hiring the van used in the attack and said he is believed to be one of the two people who have been arrested.

However, it has been reported that Oukabir has denied being involved in the attack and told police his documents had been stolen.

Police said there was no evidence the driver of the van was armed.

Officials also confirmed there were no armed men holed up in a bar near the scene, as was originally thought.

The so-called Islamic State terror group has claimed responsibility for the attack.

What has the response been from world leaders?

Prime Minister Theresa May said she was "sickened by the senseless loss of life in Barcelona" and that "Britain stands with Spain against the evil of terrorism."

US President Donald Trump condemned the attack in Barcelona and posted a message on social media saying the US "will do whatever is necessary to help. Be tough & strong, we love you!"

Belgian Prime Minister Charles Michel also sent a message of support to those caught up in the attack in Spain, tweeting "no barbaric act will undermine the power and resilience of our ally."