And reports say that a hostage situation involving two armed men is ongoing at a nearby restaurant.

In chilling echoes of the London Bridge attack, armed police have stormed La Boqueria open-air market amid claims that terrorists are armed with rifles.

Cops clad in black and carrying machine guns were seen entering the market backed up by regular police armed with pistols.

Footage has emerged of captives being released and walking towards police lines.

A huge emergency response rushed to the scene on the iconic Las Ramblas tourist hotspot at around 4pm today.

Metro lines have been shut and shoppers and pedestrians have been seen running into buildings as armed police flooded the area.

The "massive crash" involved a white van mounting the pavement, police said as they confirmed they are treating it as a terror attack.

Spanish Prime Minister Mariano Rajoy has said he is in contact with all authorities.

The driver of the Fiat van, registration 7082 JWD, ran away from the van on foot after the smash.

An operation is now underway to apprehend the person who was at the wheel.

Investigators are also hunting a SECOND van, another fiat, in connection with the attack.

Other unverified reports from local TV channel TV3 say two armed men are holding hostages in a nearby Turkish restaurant.

Cops have ordered shops and cafes in the area to shut and are searching for a man between five foot five and five foot six dressed in blue and white striped clothes.

The crash van entered the pedestrian area at the junction of Las Ramblas and Placa Catalunya.

Reports say it ploughed into people outside a Kosher food shop, although this is yet to be confirmed.

Barcelona FC wrote in a statement: "Our hearts are made smaller by this attack. Sending strength and love to the victims, their families and the citizens of Barcelona".

Marc Esparcia, a 20-year-old student who lives in Barcelona, told the BBC: "There was a loud noise and everybody ran for cover.

"There were a lot people, lots of families [at the site], this is one of the most visited sites in Barcelona.

"I think several people were hit. It was horrible, there was panic. Terrible."

He said he was now taking cover inside a Starbucks coffee shop.

Steve Garrett was in a nearby market and sheltered in a bakery with several others after streams of people ran inside.

One member of the group, who took refuge with him, said she had heard gunshots after the incident.

Mr Garrett told the BBC: "A very large number of people ran into the market area in a big kind of way, lots of screaming, lots of shouting.

"The security guards immediately responded. We ran into the bakery with four or five other people and ran straight upstairs and hunkered down whilst an enormous wave of people went through the market.

"Obviously coming from England it was reminding me a great deal of what happened in London, so we were very concerned about what might be going on next.

"The lady that was with us said she heard some gunshots."

Mr Garrett said a "second wave" of people then entered the market, followed by armed police.

He said: "They seemed to sweep through the market area. They seemed to be looking for someone. They were going very carefully, very cautiously, stall to stall."