Two attacks on Thursday and early Friday in Spain left 14 dead and more than 100 injured.

What happened?

A van ran into a crowd on Las Ramblas street in central Barcelona, an area popular with pedestrians, on Thursday in what police are treating as a terrorist attack.

Several eyewitnesses told the BBC that they heard a loud crash and screaming at the time of the attack. Witnesses told the BBC the van “had deliberately targeted people before stopping.”

Pedestrians took cover in nearby stores as authorities urged them to stay off the streets and away from the area around Plaza de Cataluna and Las Ramblas.

Catalonia police said the Barcelona attack killed 13 people and wounded at least 120 others. Authorities asked people to not circulate images of those injured.

Secretary of State Rex Tillerson confirmed Friday that at least one American was killed in the attack.

In a separate incident, several suspects drove a car into a crowd in Cambrils, a popular vacation spot along the coast southwest of Barcelona, killing one person and injuring six.

The men who exited the car appeared to be wearing explosives, police told the BBC, which turned out to be fake. But police do believe the suspects carried out a series of “controlled explosions.”

What we know

Police said they arrested two of three suspects in the Barcelona attack, according to the Associated Press.

Five suspects in the Cambrils attack were shot dead by police, CNN says.

Police say they believe the two attacks, along with a house explosion in Alcancar, are related.

What we don’t know

Spanish police have yet to determine a motive.

The AP has reported the Islamic State group is claiming responsibility for the attack, via a statement on its Aamaq news agency. Police have not yet confirmed this.

How are leaders responding?

Spain’s prime minister Mariano Rajoy tweeted that his priority was to tend to the victims in the attack.

We cannot say the reasons of this attack in BCN but the planned device was already activated in cases of consummate attack — Mossos (@mossos) August 17, 2017

President Donald Trump responded to the attack 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!” First lady Melania Trump also tweeted: “Thoughts and prayers to #Barcelona”.

The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help. Be tough & strong, we love you! — Donald J. Trump (@realDonaldTrump) August 17, 2017

Thoughts and prayers to #Barcelona — Melania Trump (@FLOTUS) August 17, 2017

On Friday, the president tweeted: “Radical Islamic Terrorism must be stopped by whatever means necessary! The courts must give us back our protective rights. Have to be tough!” The tweet appears to reference Trump’s travel ban against visitors coming to the U.S. from six mostly Muslim countries.

Radical Islamic Terrorism must be stopped by whatever means necessary! The courts must give us back our protective rights. Have to be tough! — Donald J. Trump (@realDonaldTrump) August 18, 2017

U.S. Secretary of State Rex Tillerson is offering the assistance of the U.S. embassy in Spain.

Sec. Tillerson: We offer condolences to the loss of life & the injuries that have occurred to so many innocent people yet again. #Barcelona pic.twitter.com/RKcE5MCqNB — Department of State (@StateDept) August 17, 2017

EU Commission president Jean-Claude Juncker said “We will never be cowed by such barbarism.”

My deepest condolences to the families and loved ones of the victims, to @marianorajoy and the people of #Spain. https://t.co/NQEjjuyoev — Jean-Claude Juncker (@JunckerEU) August 17, 2017

This is the latest in a series of car attacks: The Guardians says it’s the eighth such attack in Europe this year.

Last Saturday, James Alex Fields Jr., 20, drove his car into a crowd at a “Unite the Right Rally” in Charlottesville, Virginia, killing a local woman; 67 percent of Americans think the attack should be labeled as an act of domestic terrorism, according to a new poll from the PBS NewsHour, NPR and Marist.

Earlier this month, six people were injured when a BMW plowed through a group of soldiers in Paris. In June, two separate attacks in London — one on a pedestrian-filled London Bridge — killed eight and injured dozens more. The country has seen three attacks since March. The largest vehicle attack in recent memory was last July in Nice, France, when a man drove a truck into crowds celebrating Bastille Day, killing 86.

PBS NewsHour will update this story as it develops.