People wait before a minute of silence for the victims of the Barcelona attack at Plaza de Catalunya on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JAVIER SORIANO

People wait before a minute of silence for the victims of the Barcelona attack at Plaza de Catalunya on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JAVIER SORIANO

A printed black ribbon for the victims of the Barcelona attack hangs above scarfs of the FC Barcelona in a kiosk of the Rambla boulevard on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / Josep LAGO

A Union flag flies at half-mast from the roof of a building, in front of a face of the Great Clock of the Palace of Westminster's Elizabeth Tower, more commonly referred to as Big Ben, in London on August 18, 2017, following the August 17 attacks in Barcelona and Cambrils in Spain. Spanish police on Friday hunted for the driver who rammed a van into pedestrians on an avenue crowded with tourists in Barcelona, leaving 13 people dead and more than 100 injured, just hours before a second assault in a resort along the coast. / AFP PHOTO / Tolga AKMEN

Officials and people applaud after observing a minute of silence for the victims of the Barcelona attack outside Cambrils City Hall on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JOSE JORDAN

People sit next to flowers, messages, stuffed toys and others items displayed on the Rambla boulevard on August 18, 2017, to pay tribute to the victims of the Barcelona attack, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / Josep LAGO

People leave stuffed toys, candles, messages, flowers and other objects at the Canaletas fountain on the Rambla boulevard for the victims of the Barcelona attack on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JAVIER SORIANO

Catalan regional vice-President and chief of Economy and Finance, Oriol Junqueras (2ndL), Spain's King Felipe VI (7thL), Spanish Prime Minister Mariano Rajoy (6thL), President of Catalonia Carles Puigdemont (9thR), Spanish vice-President of the Government and Minister of the Presidency and of the Regional Administrations Soraya Saenz de Santamaria (5thL), Barcelona's mayor Ada Colau (8thR), President of the Catalan parliament Carme Forcadell (4thL) and officials observe a minute of silence for the victims of the Barcelona attack at Plaza de Catalunya on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JAVIER SORIANO

Stuffed toys, candles, messages, flowers and other objects are displayed for the victims of the Barcelona attack on the Rambla boulevard on August 18, 2017, a day after a van ploughed into the crowd, killing 13 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 13 people dead and injuring more than 100 others. In the first incident, which was 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 out of the way and killing 13 in a scene of chaos and horror. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / Pascal GUYOT

Anti-far-right protesters gather against a demonstration by members of the Spanish right-wing group Falange on the Rambla on August 18, 2017, a day after a van ploughed into the crowd, killing 14 persons and injuring over 100 on the Rambla in Barcelona.Drivers have ploughed on August 17, 2017 into pedestrians in two quick-succession, separate attacks in Barcelona and another popular Spanish seaside city, leaving 14 people dead and injuring more than 100 others. Some eight hours later in Cambrils, a city 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. / AFP PHOTO / JAVIER SORIANO