Police operation underway after 'possible terrorist attack' south of Barcelona

A police operation is underway in the Spanish town of Cambrils, about 90 minutes south of Barcelona, after a "possible terrorist attack," local officials said this evening.

On Twitter, police said that they "have killed the alleged perpetrators." Catalan police told ABC News that they believe the incident in Cambrils to be related to a separate attack in Barcelona earlier today.

At least 13 people died and more than 100 were injured after a van slammed into pedestrians in a busy tourist section of Barcelona's Las Ramblas district.

Two individuals have been detained, police said. One person is a Spanish national from Melilla and the other is from Morocco.

Neither of those detained was the driver of the van, police said.

ISIS has claimed responsibility for the Las Ramblas attack via its Amaq agency, according to the SITE Intelligence Group.

Catalonia's emergency services advised the community to "stay home" and "avoid going out."

Police have connected the incident to a house explosion in Alcanar, Spain, Wednesday night. The explosion, which caused part of the building to collapse, killed one person and injured others, police said.

The two people who were arrested were detained in the same town as the house explosion, authorities said.

Police described a separate incident in which a car trying to get past a Barcelona checkpoint hit an officer and another person, police said. The incident killed one person and broke the officer's leg, police said.

A man inside the car was shot by police, authorities said, but they did not confirm whether the incident was connected to the attack in Las Ramblas.

A spokesperson for the Guardia Civil, Spain's national police force, told ABC News the man who rented the van has been identified as Driss Oukabir. Police confirmed that Oukabir is one of the detained individuals.

An eyewitness told a Spanish television station that the driver of the van ran people over for nearly 1,000 feet before fleeing into a nearby Turkish restaurant.

The witness said the suspect had something in his hand but he could not tell what it was.

Police said there is no proof that the man who left the car was armed but described the incident as a terror attack that attempted to kill as many people as possible.

Some of the injured went to the hospital on their own, said Catalonia's interior minister, Joaquim Forn, said in a press conference Thursday night. The number of dead and injured victims could go up, Forn said.

Authorities are in the process of identifying the deceased, he said.

Spanish Prime Minister Mariano Rajoy expressed solidarity with the victims and their families, describing the attack as "jihadist terrorism."

Those responsible for the attack will be brought to justice, Rajoy said, stressing that the response to the terrorism needs to be global.

Barcelona residents are suffering "the same pain and the same uncertainty" as their neighbors in Madrid, Paris, Nice, Brussels and London, Rajoy said.

Forn declared three days of mourning, and a moment of silence will be held on Friday at noon local time at the Plaza de Catalunya, Forn said. The king of Spain, Felipe VI, will be present for the moment of silence, the palace's official Twitter account announced.

Las Ramblas is a popular tourist area in Spain's second-largest city and was filled people at the time of the attack, police said. Catalan police ordered an evacuation of the area.

Emergency services for the Catalonia region, of which Barcelona is the capital, posted tweets in multiple languages advising individuals to use social media to inform relatives of their whereabouts.