Barcelona Las Ramblas attack

Catalan police officers, known as Mosso d’Esquadra, stand guard outside a house in Ripoll during a search linked to the Barcelona and Cambrils attacks on Aug. 18, 2017.

Mourners pack Plaza de Catalunya as authorities (front) observe a minute of silence in Barcelona on Aug. 18, 2017.

Mourners pack Las Ramblas, the scene of a fatal terror attack the day before, for a minute of silence on Aug. 18, 2017, in Barcelona.

Spain’s King Felipe VI, second left, and Spanish Prime Minister Mariano Rajoy, left, join the president of Catalonia, third left, and Barcelona’s mayor, second right, prior to a minute of silence for the victims of the Barcelona attack at Plaza de Catalunya on Aug. 18, 2017.

Staff at the Spanish Embassy in London pause for a minute’s silence on Aug. 18, 2017, following the Aug. 17 attacks in Barcelona and Cambrils in Spain.

People leave the Plaza de Catalunya after observing a minute of silence for the victims of the Barcelona attack on Aug. 18, 2017.

A woman lights a candle next to flowers, messages and stuffed toys left for victims on the spot where a van powed into a crowd on Las Ramblas in Barcelona.

A bouquet with a note reading “Catalonia with you, Barcelona and Cambrils” hangs from the fence of the Spanish Embassy in Berlin, Germany, on Aug. 18, 2017.

A police officer walks near gas canisters in Alcanar, Spain, during a search on Aug. 18, 2017. The site is thought to be linked to the Barcelona and Cambrils attacks, and was the scene of a fatal explosion on Aug. 16.

A screengrab from a video shows a police officer standing on a road in Alcanar, about 120 miles south of Barcelona, at the scene of an explosion in a house that left one person dead and seven wounded on Aug. 16, 2017. The explosion is believed to be linked to the attack in Barcelona on Aug. 17.

A van that was driven into a crowd, killing at least 13 people and injuring about 100 others, is towed away from Las Ramblas in Barcelona on Aug. 18, 2017.

A damaged van, believed to be the one used in the attack, is surrounded by police officers in the Las Ramblas area on August 17, 2017, in Barcelona, Spain.

Injured people react after a van crashed into pedestrians in Las Ramblas, downtown Barcelona, Spain, August 17, 2017.

Spanish policemen accompany people leaving the cordoned off area after a van ploughed into the crowd, killing 13 persons and injuring over 50 on the Rambla in Barcelona on August 17, 2017.

Spanish policemen stand guard in a cordoned off area after a van plowed into the crowd, killing 13 persons and injuring over 50 on the Rambla in Barcelona on August 17, 2017.

Policemen check the identity of people standing with their hands up after a van plowed into the crowd on the Rambla in Barcelona on August 17, 2017.

Injured people react after a van crashed into pedestrians in Las Ramblas, downtown Barcelona, Spain, August 17, 2017.

People comfort each other after a van plowed into the crowd on the Rambla in Barcelona on August 17, 2017.

People flee the scene in Barcelona, Spain, Thursday, Aug. 17, 2017 after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists.

People leave a cordoned off area after a van plowed into the crowd on the Rambla in Barcelona on August 17, 2017.

People flee from the scene after a white van jumped the sidewalk in the historic Las Ramblas district of Barcelona, Spain, crashing into a summer crowd of residents and tourists Thursday, Aug. 17, 2017.

An injured person is carried in Barcelona, Spain, Thursday, Aug. 17, 2017, after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists and injuring several people, police said.

A woman is comforted as crowds flee from the scene after a white van jumped the sidewalk in the historic Las Ramblas district of Barcelona, Spain, crashing into a summer crowd of residents and tourists Thursday, Aug. 17, 2017.

People speak on their phones as they stand on a street in Barcelona, Spain, Thursday, Aug. 17, 2017. Police in the northern Spanish city of Barcelona say a white van has jumped the sidewalk in the city’s historic Las Ramblas district, injuring several people.

A person is treated in Barcelona, Spain, Thursday, Aug. 17, 2017 after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists and injuring several people, police said.

People flee the scene in Barcelona, Spain, Thursday, Aug. 17, 2017 after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists and injuring several people, police said.

Injured people are treated in Barcelona, Spain, Thursday, Aug. 17, 2017 after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists and injuring several people, police said.

A person is carried in Barcelona, Spain, Thursday, Aug. 17, 2017 after a white van jumped the sidewalk in the historic Las Ramblas district, crashing into a summer crowd of residents and tourists and injuring several people, police said.

TOPSHOT - People leave a cordoned off area after a van ploughed into the crowd, killing one person and injuring several others on the Rambla in Barcelona on August 17, 2017.

People react as they leave a cordoned off area after a van ploughed into the crowd, killing two persons and injuring several others on the Rambla in Barcelona on August 17, 2017.

A woman cries as she phones after a van ploughed into the crowd, killing one person and injuring several others on the Rambla in Barcelona on August 17, 2017.

People leave a cordoned off area after a van ploughed into the crowd, killing two persons and injuring several others on the Rambla in Barcelona on August 17, 2017.

Two young girls run to leave a cordoned off area after a van ploughed into the crowd, killing two persons and injuring several others on the Rambla in Barcelona on August 17, 2017.

Children are escorted down a road in Barcelona, Spain after a white van mounted a sidewalk and struck several people in the city’s Las Ramblas district on Aug. 17, 2017.

Emergency medical workers move an injured man after a white van mounted a sidewalk and struck several people in the Barcelona’s Las Ramblas district on Aug. 17, 2017.

A person is stretchered out of a store by medical staff in a cordoned off area after a van plowed into a crowd on Las Ramblas in Barcelona on Aug. 17, 2017.

A police officer cordons off a street in the Las Ramblas historic disctrict of Barcelona on Aug. 17, 2017.