Abouyaaqoub fled the attack on foot, then killed another person in order to steal the victim's car to make his escape.

[2][3][4] Nine hours after the Barcelona attack, five men thought to be members of the same terrorist cell drove into pedestrians in nearby Cambrils, killing one woman and injuring six others.

[5] The night before the Barcelona attack, an explosion occurred in a house in the Catalan town of Alcanar, destroying the building and killing two members of the terrorist cell, including the 40-year-old imam thought to be the mastermind.

[13] At 16:56 CEST (UTC+2) on 17 August 2017,[14] Younes Abouyaaqoub drove a white Fiat Talento van onto the pavement of Barcelona's La Rambla, crashing into pedestrians for about 550 metres (1,800 ft) between Plaça de Catalunya and Liceu before stopping on the Joan Miró mosaic.

[20][21] About two hours after the attack on La Rambla, a white Ford Focus rammed a police barricade in Avinguda Diagonal, leaving an officer injured.

The police found a man stabbed to death in the rear seat who, they believe, was murdered by the Ramblas driver who had escaped by hijacking the car.

There was speculation that the terrorists intended to take trucks loaded with explosives and combustible gas to attack the Sagrada Família.

[29] Police said they were working under the hypothesis that the terrorists shot in Cambrils were connected to the Barcelona attack and Alcanar explosions.

[30] Police chief Josep Lluís Trapero believed terrorists were in the process of manipulating the gas canisters when they exploded, after which they decided to continue their plans by conducting more rudimentary vehicle ramming attacks.

[31] A second explosion occurred at the same location during excavation, possibly caused by a spark from a backhoe igniting a gas canister among the debris.

They stabbed a 63-year-old Spanish woman to death[36] and injured six other people in the attack, including a Cuban tourist and a police officer.

[4] The imam Abdelbaki Es Satty died in the Alcanar gas explosion on 16 August,[97] as did Youssef Aalla, brother of Said Aallaa.

[118] In 2015, when asked on the social media website Kiwi what he would do in his first day as king of the world, he responded, "Kill the infidels and only spare Muslims who follow the religion.

[115][125] La Vanguardia reported that Aallaa's social media contained photographs of firearms and that his religiosity was evidenced by his membership in Islamic study groups.

He was the brother of fellow attacker Mohamed Hychami, and the cousin of the Rambla van driver Younes Abouyaaqoub.

[145] He has been described as "unfailingly courteous and studiously discreet", betraying no radicalism in his appearance and interactions with those who did not know him, and training those in his terrorist cell to also lead double lives.

[148] By 24 August 2017, two of the suspects, Salh El Karib and Mohamed Aalla, had been released on certain conditions, including that they hand over their passports.

[153] The day after the attacks, a minute's silence led by King Felipe VI, Catalan president Carles Puigdemont, and Barcelona mayor Ada Colau was observed at Plaça de Catalunya, which ended with applause and chants of "No tinc por" ("I am not afraid").

[154] During the following days candles and flowers were left at the Joan Miró mosaic at La Rambla, in memory of the victims.

Some people booed the King of Spain and displayed signs blaming the Head of State for the Spanish arms sales.

[156][157][158][159] On 10 September 2017, the security and emergency services were awarded the Medal of Honour of the Catalan Parliament (Medalla d'Honor del Parlament de Catalunya).

With this medal the Catalan Parliament recognises the dedication, effort, and courage of the Mossos d'Esquadra, Guàrdia Urbana de Barcelona, Local Police of Cambrils, and the Emergency Services.

The Major of the Catalan Police, Josep Lluís Trapero Álvarez, collected the award and made a speech mourning the victims.

[160] Many world leaders reacted to the events, condemning the attacks and expressing shock and solidarity with Spain, as well as offering support.

[164] The Interior Ministry and the Cuerpo Nacional de Policía recommended the installation of bollards, but the Generalitat chose to increase the presence of police officers instead.

[170] The first author of the video was identified as Abu Lais Al Qurtubí (el Cordobés in Spanish)[171] or Abu Laiz al Qurtubi,[172] named Muhammad Yasin Ahram Pérez,[173] Tomasa Pérez's oldest son, who converted to Islam after her marriage to the Moroccan Abdelah Ahram.

[181][182] In January 2022, former police commissioner José Manuel Villarejo, appeared to suggest that the Spanish authorities knew of Younes Abouyaaquob's plans ahead of time and used it to hamstring the Catalonian Independence movement, prompting Catalan president Pere Aragonès to call for an investigation.

[12][183][13] In 2020, Catalan journalist Anna Teixidor published a book about the attacks titled Sense por de morir: Els silencis del 17-A.