A white van jumped up onto a sidewalk and sped down a pedestrian zone Thursday in Barcelona’s historic Las Ramblas district, swerving from side to side as it plowed into tourists and residents. Police said 13 people were killed and more than 100 wounded in the terror attack. Authorities expected the death toll to rise due to the number of critical injuries.

Video posted to social media show emergency services at the scene. Some images show injured people in front of “Maccabi“, which is a Shomer Shabbos, Kosher restaurant.

UPDATE: 13 people confirmed dead and over 100 injured in Barcelona terror attack – Catalan’s Interior Minister

— Breaking911 (@Breaking911) August 17, 2017

“It was clearly a terror attack, intended to kill as many people as possible,” Josep Lluis Trapero, senior police official, told a news conference late Thursday.

ISIS has claimed responsibility for the attack, saying in a statement on its Aamaq news agency that the attack was carried out by “soldiers of the Islamic State” in response to the extremist group’s calls for followers to target countries participating in the coalition trying to drive it from Syria and Iraq..

BREAKING: ‘Amaq News Agency reported #ISIS responsibility for #Barcelona attack #Spain pic.twitter.com/W8FFz7qBz6

— SITE Intel Group (@siteintelgroup) August 17, 2017

The attack left people sprawled out on the ground in the city in northeastern Spain, some spattered with blood, others crippled with broken limbs. Others fled in panic, screaming or carrying young children in their arms. As witnesses and emergency workers tried to help the wounded, swarms of police brandishing hand guns and automatic weapons launched a manhunt in the downtown district, ordering stores and cafes and public transport to shut down. They asked people to stay away from the area so as not to get in the way of emergency services. A helicopter hovered over the scene.

Several hours later they reported two arrests, one a Spanish national from Melilla, a Spanish-run enclave in North Africa, and the other a Moroccan, but Trapero said neither of them was the driver of the van. The arrests took place in the northern Catalan town of Ripoll and in Alcanar, the site of a gas explosion at a house on Wednesday night. Police said they were investigating a possible link to Thursday’s attack.

BREAKING: Police Confirm Driver of Van In Barcelona Attack Is Still On The Run – Fox News

— Breaking911 (@Breaking911) August 17, 2017

State-owned broadcaster RTVE reported that investigators think two vans were used — one for the attack and a second as a getaway vehicle.

WATCH: Scene after van plows pedestrians in Barcelona, Spain pic.twitter.com/zasSKhnkSG

— Breaking911 (@Breaking911) August 17, 2017

Las Ramblas, a street of stalls and shops that cuts through the center of Barcelona, is one of the city’s top tourist destinations. People walk down a wide, pedestrian path in the center of the street but cars can travel on either side.

A taxi driver who witnessed the attack, Oscar Cano, told TV3 the van jumped onto the central pedestrian area at a high speed and swerved from side to side.

In photographs and videos, dozens people could be seen lying on the ground in the street Thursday afternoon, being helped by police and others. Other video recorded people screaming as they fled the van.

Keith Fleming, an American who lives in Barcelona, was watching TV in his building just off Las Ramblas when he heard a noise and went out to his balcony.

“I saw women and children just running and they looked terrified,” he said.

He said there was a bang — possibly from someone rolling down a store shutter — and more people ran by. Then police arrived and pushed everyone a full block away. Even people leaning out of doors were being told to go back inside, he said.

Fleming said regular police with guns drawn and riot police were at the end of his block, which was soon deserted.

“It’s just kind of a tense situation,” Fleming said. “Clearly, people were scared.”

Carol Augustin, a manager at La Palau Moja, an 18th-century place on Las Ramblas that houses government offices and a tourism center, said the van passed right in front of the building.

“We saw everything. People started screaming and running into the office. It was such a chaotic situation. There were families with children. The police made us close the doors and wait inside,” she said.

U.S. President Donald Trump wrote on Twitter: “The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help. Be tough & strong, we love you!”

U.S. Secretary of State Rex Tillerson offered assistance to authorities in Spain and said U.S. diplomats in Spain were helping Americans there. He vowed the United States would never relent in tracking down terror suspects and holding them to account.

“Terrorists around the world should know that the United States and our allies are resolved to find you and bring you to justice,” Tillerson said in a statement.

British Prime Minister Theresa May said the U.K. “stands with Spain against terror.” European Commission President Jean-Claude Juncker said “this cowardly attack has deliberately targeted those enjoying life and sharing time with family and friends. We will never be cowed by such barbarism.”

Spain has been on a security alert one step below the maximum since June 2015 following attacks elsewhere in Europe and Africa. Spanish police have also been involved in the arrests of more than 200 suspected jihadis since then.

Cars, trucks and vans have been the weapon of choice in multiple extremist attacks in Europe in the last year.

The most deadly was the driver of a tractor-trailer who targeted Bastille Day revelers in the southern French city of Nice in July 2016, killing 86 people. In December 2016, 12 people died after a driver used a hijacked trick to drive into a Christmas market in Berlin.

There have been multiple attacks this year in London, where a man in a rented SUV plowed into pedestrians on Westminster Bridge, killing four people before he ran onto the grounds of Parliament and stabbed an unarmed police officer to death in March.

Four other men drove onto the sidewalk of London Bridge, unleashing a rampage with knives that killed eight people in June. Another man also drove into pedestrians leaving a London mosque later in June.

JUST IN: US DEPARTMENT OF HOMELAND SECURITY ISSUES STATEMENT ON BARCELONA ATTACK – https://t.co/dLXkn7eBLO pic.twitter.com/2hQ5cXPW33

— Breaking911 (@Breaking911) August 17, 2017

The most deadly was the driver of a tractor-trailer who targeted Bastille Day revelers in the southern French city of Nice in July 2016, killing 86 people. In December 2016, 12 people died after a driver used a hijacked trick to drive into a market in Berlin.

There have been multiple attacks this year in London, where a man in a rented SUV plowed into pedestrians on Westminster Bridge, killing four people before he ran onto the grounds of Parliament and stabbed an unarmed police officer to death in March.

Four other men drove onto the sidewalk of London Bridge, unleashing a rampage with knives that killed eight people in June. Another man also drove into pedestrians leaving a London mosque later in June.

DEVELOPING STORY – REFRESH FOR UPDATES

Statement From New York Governor Cuomo on Barcelona Terror Attack pic.twitter.com/pGPKObtkOl

— Breaking911 (@Breaking911) August 17, 2017