On Thursday afternoon, a van rammed into a crowd of people in Barcelona, killing 13 people and injuring at least 100.
It’s the worst attack on Spanish soil since the 2004 Madrid bombings, which killed 191 people and injured more than 1,800.
As the country mourns and police continue to search for answers, here’s what we know so far.
When and where did the attack happen?
Around 5 p.m. local time (11 a.m. ET), reports of the incident emerged on social media.
A white van with blue markings accelerated into scores of people enjoying a late afternoon stroll on Las Ramblas, a predominantly pedestrian zone in the heart of the Catalan capital.
The popular tree-lined street runs around three-quarters of a mile through the city center and is one of Barcelona’s most popular locales, boasting a number of the city’s most visited sites as well as cafes, bars, street performers and entertainment.
As the attack unfolded, some took shelter in nearby shops, barricading themselves against the terror as they watched scenes of chaos and panic continue.
Ali Shirzainia was cycling when he saw the van drive past him. “I saw people flying into the air and everyone was running into the shops on either side,” he told CNN.
“I saw a lot of ambulances, I saw a lot of emergency vehicles almost immediately,” he said.
Another witness who was hiding in a shop nearby heard gunshots, according to state-run broadcaster TVE24. A third said he saw a van driving “around 80” kph (50 mph).
Who is responsible?
Spanish Prime Minister Mariano Rajoy described the attack as “jihadi terrorism” during a news conference late Thursday. The perpetrators’ motive is still unclear.
The driver of the van escaped and is still on the run, according to police.
Two other suspects have been arrested. At a news conference on Thursday, the head of Catalonia Police said one of the suspects is from Morocco and the other is from the Spanish enclave of Melilla.
ISIS’ media wing, Amaq, issued a statement that said the attackers are “soldiers of the Islamic State,” although ISIS has not explicitly claimed responsibility for the attack. The terror group has not mentioned any names nor did it post any photos or additional details about the perpetrators.
Were there multiple attacks?
It’s not clear.
Catalan police said on Twitter in the early hours of Friday that an incident in Cambrils, a coastal city around 100 kilometers from Barcelona, was being treated as a possible terror attack.
State broadcaster TVE said that five terrorists were taken down, and four are dead.
In a separate incident earlier, police tweeted that a driver had run over two police officers at a security checkpoint in Barcelona and that the driver had been found near the city.
The two officers suffered minor injuries but did not require hospitalization, according to police. It was unclear whether that incident was related to the terror attack.
One person was killed in an explosion in a house in Catalonia, according to Spanish police. The incident is connected to the Barcelona van attack, but it’s not clear how. That victim is Spanish and was not on police radar.
Who are the victims?
By Thursday evening, Catalan Minister of the Interior Joaquim Forn said 13 people had died. At least 100 people were injured, with 15 of them in serious condition.
Local officials have said the number of dead is “bound to rise.”
One Belgian was killed in the attack, Belgian Foreign Ministry spokesman Jose de Pierpont said.
Catalan authorities have dismissed local media reports that had said a hostage situation took place after the crash.
Police sealed off the area and advised that people avoid the Plaça de Catalunya and Las Ramblas vicinity.
All scheduled public events were canceled. The metro station and other train stations in the vicinity were temporarily closed.
How are leaders responding?
Rajoy tweeted that terrorists “will never defeat a united people who love freedom versus barbarism.”
German Chancellor Angela Merkel called the attack in Barcelona, “revolting,” according to her spokesman.
US President Donald Trump said: “The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help. Be tough & strong, we love you!” He later tweeted about a debunked episode related to countering Islamic terrorism.
Anne Hidalgo, mayor of Paris, tweeted that the Eiffel Tower would go dark Thursday night in tribute to the victims.