rmed Catalan Mossos d'esquadra officers stand guard at Las Ramblas street where a van crashed into pedestrians in Barcelona, Spain, August 18, 2017.

Among the 100 or more people who were injured in the attack in Barcelona on Thursday are 26 French citizens, at least 11 of whom are in a serious condition, French Foreign Minister Jean-Yves Le Drian said Friday.

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For his part, Interior Minister Gerard Collomb told RTL radio that "the number of those who have been seriously injured may perhaps be even higher at around 17."

Expressing his "deep emotion" over the attack, Le Drian said in a statement that he would travel to Barcelona on Friday "to visit the French victims of this cowardly act and affirm France's support to the Spanish people and authorities."

President Emmanuel Macron earlier said France and Spain remain "united" after the "tragic attack".

In an incident claimed by the Islamic State group, a white van sped into a street packed full of tourists in central Barcelona on Thursday afternoon, knocking people over and killing 13 in a scene of chaos and horror.

Some eight hours later in Cambrils, a town 120 kilometres south of Barcelona, an Audi A3 car rammed into pedestrians, injuring six civilians -- one of them critical -- and a police officer, authorities said.

There were at least 18 nationalities among the dead and injured, who came from countries as varied as France, Italy, Venezuela, Australia, Ireland, Peru, Algeria and China, according to Spain's civil protection agency.

One Belgian was among the dead, said Belgium's foreign minister Didier Reynders.

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