Barcelona and Real Madrid are among those to have expressed their sadness at the terror attack in the Catalan capital on Thursday in which 13 people died and dozens were injured.

A van ploughed into pedestrians in the busy tourist area of Las Ramblas on Thursday. Police are treating it as a terrorist attack.

The BBC reports that the vehicle sped along the pedestrian area, mowing down people and sending others fleeing for cover.

Barcelona said on Twitter: "Deeply saddened by the attack on our city. All our thoughts are with the victims, their families and with the people of Barcelona."

#TotsSomBarcelona Our thoughts are with the victims of the Barcelona attack👇 https://t.co/wi7yiUH5qK

— FC Barcelona (@FCBarcelona) August 17, 2017

Luis Suarez was among the Barcelona players who added their shock and support.

Very shocked for what happened in Barcelona. All my support to the city and families! pic.twitter.com/YDtyAiw7Qc

— Luis Suarez (@LuisSuarez9) August 17, 2017

Andres Iniesta added: "Dismayed by what has happened and the news that we keep getting from our city. All my love."

Todos consternados por lo que ha pasado y las noticias que siguen saliendo desde nuestra ciudad. Todo mi cariño. pic.twitter.com/CIhEKncx4A

— Andrés Iniesta (@andresiniesta8) August 17, 2017

Their La Liga rivals Madrid said in a statement on their website: "Real Madrid show their deepest dismay at the attack in the city of Barcelona and express their solidarity with the victims and their families and friends and at the same time wish the injured a speedy recovery."

Real Madrid striker Cristiano Ronaldo, who was sent off in Monday's Supercopa first leg at the Nou Camp, added on Twitter: "Dismayed at the news coming from Barcelona. All the support and solidarity with the family and friends of the victims."

Consternado com as notícias que chegam de Barcelona. Todo o apoio e solidariedade a família e amigos das vítimas.

— Cristiano Ronaldo (@Cristiano) August 17, 2017

Ronaldinho won two league titles and the Champions League during a glittering five-year spell at the Nou Camp, during which he also won the Ballon d'Or.

The Brazilian tweeted: "Too sad to see the news coming from #Barcelona. My support and solidarity for the victims and families."

Former England striker Gary Lineker played for Barcelona for three seasons from 1986-89.

He tweeted: "Deeply saddened to hear about the attack in the wonderful city of Barcelona. What purpose this barbarity serves is beyond comprehension."

Manchester City, managed by former Barcelona midfielder and manager Pep Guardiola, said: "All at MCFC are saddened to hear of the attack in the City of Barcelona. Our thoughts are with all affected and the emergency services."

Spain's 15-time grand slam champion Rafael Nadal, whose uncle Miguel Angel Nadal played for Barca from 1991-99, said: "Shattered by what has happened in Barcelona! All my support for the families affected and the city."

Espanyol, the city of Barcelona's other top-flight team, tweeted: "The most beautiful city in the world, our city. We suffer with you and with all the people of Barcelona. Strength and encouragement, Barcelona!"

Atletico Madrid added: "Shocked by the terrible news coming from Barcelona; All our support for the victims and their families."

Serie A giants AC Milan tweeted: "Everyone at #ACMilan deeply regrets the attack in Barcelona. Our deepest condolences to all those affected."

Former Manchester United defender Rio Ferdinand said: "Shocking to see the news in Barcelona... My thoughts are with the victims & their families!"

United added their support and sadness.