Islamic State claimed responsibility for the deadly rampage along the city’s most famous avenue on Thursday, which was packed with tourists taking an afternoon stroll. The death toll could rise, with more than 100 injured, authorities said.

As security forces hunt for the van’s driver, who was seen escaping on foot, police killed four attackers on Thursday night in Cambrils, a town south of Barcelona, to thwart a “terrorist attack” using explosive belts. Six civilians and a police officer were injured in the operation.

Police say the Cambrils plot was linked to the van attack.

Before the van ploughed into the tree-lined walkway of Las Ramblas, one person was killed in an explosion in a house in a separate town southwest of Barcelona, police said. Residents there were preparing explosives, a police source added.

Three Australians have been caught up in the attack in Barcelona, with one woman from New South Wales in a serious but stable condition and two men, from Victoria, also hurt, Australia’s Foreign Minister Julie Bishop said.

Police have arrested two men, a Moroccan named as Driss Oukabir, 28, and a man from Spain’s north African enclave of Melilla, though neither was the van driver. A manhunt is ongoing for the driver and the Cambrils situation is under control.

Witnesses to the van attack said the white vehicle had zigzagged at high speed down Las Ramblas, ramming pedestrians and cyclists, sending some hurtling through the air and leaving bodies strewn in its wake.

Islamic State’s Amaq news agency said: “The perpetrators of the Barcelona attack are soldiers of the Islamic State and carried out the operation in response to calls for targeting coalition states” – a reference to a U.S.-led coalition against the Sunni militant group.

Spain has several hundred soldiers in Iraq providing training to local forces in the fight against Islamic State, but they are not involved in ground operations.

The Islamic State claim could not immediately be verified.

If the involvement of Islamist militants is confirmed, it would be the latest in a string of attacks in the past 13 months in which they have used vehicles to bring carnage to the streets of European cities.

That modus operandi – crude, deadly and very hard to prevent – has killed well over 100 people in Nice, Berlin, London and Stockholm.

British tourist Keith Welling, who arrived in Barcelona on Wednesday with his wife and 9-year-old daughter, said they saw the van drive past them down the avenue and took refuge in a restaurant when panic broke out and the crowd started running.

“People were shouting and we heard a bang and someone cried that it was a gunshot … Me and my family ran into the restaurant along with around 40 other people.

“At first people were going crazy in there, lots of people crying, including a little girl around three years old.”

It was the deadliest attack in Spain since March 2004, when Islamist militants placed bombs on commuter trains in Madrid, killing 191 people and wounding more than 1,800.

Spanish Prime Minister Mariano Rajoy announced three days of official mourning for what he called a “jihadist attack.”

The Spanish royal household said on Twitter: “They are murderers, nothing more than criminals who are not going to terrorise us. All of Spain is Barcelona.”

US President Donald Trump said: “The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help.”

He added: “Be tough & strong, we love you!”

Police said the two men detained on Thursday had been arrested in two towns, Ripoll and Alcanar, both in the region of Catalonia, of which Barcelona is the capital.

The explosion was also in the town of Alcanar, in the early hours of Thursday. One person died and another was injured in that incident, police said.

– Reuters