BARCELONA -- At least 13 people were killed and more than 50 injured after a van rammed through crowds of people in the heart of Barcelona Thursday in what police described as a terror attack.
Eyewitnesses reported scenes of panic and chaos as the van plowed through crowds in the renowned Las Ramblas avenue, which was teeming at the time with locals and tourists.
One person has been arrested, Catalan police said. Police were treating the incident as an act of terrorism and sealed off the area.
"We can confirm 13 dead and more than 50 injured," Joaquim Forn, the Catalan interior minister, told a news conference.
City officials ordered all public events to be canceled, while metro and train stations in the area were closed.
Reports of the attack first emerged on social media at about 5 p.m. local time (11 a.m. ET). About two hours later, police confirmed that Spain had suffered a deadly attack.
It was the latest in a series of attacks in Europe in which vehicles have been used to mow down pedestrians in public spaces. More than 100 people have died in similar attacks in Berlin, London and Nice.
Catalan police said they were continuing to hunt for the perpetrators and that the force had activated its terror response protocols. Unconfirmed reports suggested the suspects may have been attempting to reach a getaway vehicle.
Local Spanish media earlier reported that two armed men had entered a restaurant. But Catalan police dismissed rumors that the attacker had been holed up near Las Ramblas and said there "was never a hostage situation."
As the incident unfolded, police told everyone in the vicinity of Plaça de Catalunya and Las Ramblas to remain indoors until told it was safe to go outside. Footage posted to social media by witnesses showed chaotic scenes with people lying in the street, apparently dead or injured.
Witness reports gunshots
One witness told local media the situation was "very tense" and that all surrounding shops were being evacuated. The witness said at least eight ambulances were at the scene. Emergency services said the area had been cordoned off and all public transportation stopped.
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 kilometers" per hour, or 50 mph. He said "there is no doubt it was intentional," according to TVE24.
Tourist Susan McClean told CNN that she saw a "tidal wave" of people running away from Las Ramblas in the aftermath of the incident.
She ducked into a nearby shop and the shutters were pulled down while police sped toward the scene.
"There was clearly a lot of distress," she told CNN.
McClean said she returned to her hotel just a street away after leaving the shop.
Witness: 'Lot of distress'
The Catalan regional government said it was holding an emergency meeting to discuss the incident.
The Catalan emergency services urged people via Twitter to avoid going out or undertaking any other type of movement that is not "strictly necessary" to facilitate police operations.
Spanish Prime Minister Mariano Rajoy tweeted: "The terrorists will never defeat a united people who love freedom versus barbarism. All of Spain is with the families and their victims."
The Spanish royal family tweeted: "They are assassins, simply criminals who are not going to terrorize us. All of Spain is Barcelona. Las Ramblas will return to be everyone's."
NATO chief: We stand united
World leaders were quick to voice their condemnation of the attack and offer support to Barcelona via Twitter.
"My thoughts are with all those affected. We stand united in the fight against terrorism," said NATO Secretary General Jens Stoltenberg.
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!"
London Mayor Sadiq Khan also gave his support, saying: "London stands with Barcelona against the evil of terrorism."
German Chancellor Angela Merkel called the attack in Barcelona "revolting," her spokesman tweeted. "We are mourning the victims of this disgusting attack in Barcelona -- in solidarity and friendship side by side with the Spanish."
European Commission President Jean-Claude Juncker branded the Barcelona attack "cowardly," adding: "We will never be cowed by such barbarism."
Las Ramblas is a predominantly pedestrianized street popular among tourists in Barcelona. Extending for about three-quarters of a mile through the center of the city, the tree-lined street is especially crowded in the summer, the height of tourist season.
The promenade passes by kiosks, flower sellers, pavement cafes and bars. It includes a number of the city's most popular sites.