Officials have confirmed at least 13 people have died and 100 have been injured after a van mounted a pavement in Barcelona.

It follows what the country's Department of the Interior described as "a massive trampling on the Ramblas in Barcelona by a person with a van".

Shortly after the crash the Interior confirmed it as a "terrorist attack", the department tweeted: "The terrorist attack protocol has been activated".

A senior police official later said it was "clearly a terror attack, intended to kill as many people as possible".

So-called Islamic State has claimed responsibility for the attack.

A couple of hours after the attack the Interior ministry dismissed early reports that suspects being sought in connection with the attack had been holed up in a Barcelona bar saying there was"no one entrenched" in any bar in the centre of the city.

Catalonia's regional president Carles Puigdemont confirmed in a press conference late on Thursday that police had made two arrests following the attack but it was later said neither of the suspects being held was the driver.

A senior police official said the two arrested suspects are a Spanish national from Melilla and a Moroccan.

Local media have named Driss Oukabir as the man suspected of hiring the white Fiat van used in the attack and said he is believed to be one of the two people who have been arrested although this has not been officially confirmed.

Police in Barcelona cordoned off the area and asked people to stay away from the scene after the white van mounted a pavement and struck several people in the busy tree-lined city centre promenade on Thursday afternoon.

Images posted on social media shortly after the crash appeared to show people lying on the street being treated for injuries and a photograph shown by public broadcaster RTVE showed at least three people on the ground apparently being helped by police.

Eyewitnesses said they saw people running away and screaming after the incident happened as the driver of the van was reported to have fled on foot.

Another eyewitness Aamer Anwar, who was walking down Las Ramblas at the time of the crash, said the area was "jam-packed" with tourists when the van mounted the pavement.

Mr Anwar described the scene as "chaos" and said: "I turned around and people were screaming - I could see a woman screaming with her kids - people started running and jumping into shops. I ran for about 50 or 100 metres and stopped to see what was happening. The police were very quickly on the scene and getting people to move back.

"I could see chaos right at the top area and I spoke to a shopkeeper who had run down and was screaming. He was Bengali so I spoke to him in Urdu and he said a van had driven into a crowd and he thought there were five to six people very seriously injured."

He also tweeted a video of the scene along with a message which read: "Can't believe this I'm on Ramblas, heard screaming & whole street ran- a car believed drove in2crowd- had walked down 10secs earlier." said:

In a different video shared on Twitter by social media user Arturo Fernandez Rui police can be seen surrounding the main stretch of Las Ramblas in the aftermath of the attack.

In a second video, showing more police rushing to the scene, Mr Rui wrote: "The horror comes to our city."

Simon Manley, the British ambassador to Spain, has confirmed the Foreign Office is "in contact with the authorities and seeking further information following the incident".

While a Foreign Office spokesman said they were "in contact with the Spanish authorities and seeking more information following an incident in Barcelona" and "anyone in the area should follow the advice of the emergency services."

Barcelona's Mayor has announced that a minute's silence will be held on Friday in the city's main square 'to show that we are not scared' after van attack.

World leaders react to attack

Catalonia's regional president Carles Puigdemont described the attack as "shocking" and pledged "all of us will join together to defeat those who use violence. Barcelona, Catalonia is a city of peace"

Prime Minister Theresa May said her thoughts are with the victims of the "terrible attack" in Barcelona, tweeting: "The UK stands with Spain against terror."

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!"