In a photograph shown by public broadcaster RTVE, three people were lying on the ground in the street of the northern Spanish city Thursday afternoon, apparently being helped by police and others.
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.
Tom Gueller, who lives on an adjoining road, fled the scene when he saw the van hurtling through the crowds. ISIS has claimed responsibility.
"We work on the hypothesis that terrorists killed in Cambrils would be related to the events registered in Barcelona and Alcanar", Catalan authorities tweeted. The officials also claimed that the situation is under control while adding that a suspect was injured during the anti-terror operations in South Barcelona and has been arrested.
Spanish Prime Minister Mariano Rajoy will travel to Barcelona with his deputy and interior minister.
The El Mundo newspaper quoting police sources said the police prevented another terrorist attack in Cambrils town of Tarragona, a port province in northeast Spain, hours after the attack in Barcelona.
Parsons, who said he rarely goes to Las Ramblas, started walking in the same direction that everyone was running.
Police later confirmed six people had been injured and that all five terrorists had been killed.More news: The Magellan Midstream Partners LP (MMP) Stake Increased by National Planning Corp
At least one person was killed and many more wounded after a van was driven onto a sidewalk and down a pedestrian zone in Barcelona's historic Las Ramblas district.
Authorities in Barcelona, Spain respond after a van plows into crowds at the city's popular Las Ramblas district.
Oregon State said it has not yet determined the remaining schedule for the team, which was supposed to be on the exhibition tour until August 25.
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 USA -led coalition against the Sunni militant group.
Some eight hours later in Cambrils, a city 120 kilometres south of Barcelona, an Audi A3 vehicle hit pedestrians, injuring six civilians - one of them in a critical condition - and one police officer, said the government of the Spanish region of Catalonia where both cities are located. The police arrested two suspects.
The vehicle careered into terrified pedestrians in the busy tree-lined promenade, one of the most popular parts of the city.
Mossos, Catalonia's police force, said four of the attackers were shot dead at the scene and later confirmed a fifth had died of his injuries. Spanish police have also been involved in the arrests of more than 200 suspected jihadis since then.
Local media reports said a white Ford Focus ran over the officers and that a person from the vehicle was shot and killed by officers.