The previously unseen pictures were reportedly leaked from the Spanish police investigation into the terror attack that left 16 people dead.
In the photos, the terrorists can be seen in a room manufacturing up to 500kg of explosives – known as the Mother of Satan – in the city of Alcanar. Police say the bombs were packed into pillowcases along with homemade grenades and a suicide vest, but, fortunately, they exploded before they could be used.
The group was prompted to switch tactics after the explosion in Alcanar on August 16 and instead launched a van attack on Las Ramblas the next day, killing 13 and injuring more than 100.
A man was stabbed to death the same day and his car was used to ram a police barricade. The following day, another car attack was carried out in Cambrils, which left one woman dead and several others wounded.
The attacks came to an end on August 18 when one of the terrorists, Younes Abouyaaqoub, was killed during a shootout with police. The 22-year-old, who was later identified as the driver of the van in the Las Ramblas attack.
Younes Abouyaaqoub can be seen in the photos joking as he builds bombs. Also seen in the images is Youssef Aalla, who was killed in the explosion in Alcanar, and Mohamed Houli Chemlal, who survived it and is currently on trial. Omar Hichamy and Mohamed Hichamy were shot and killed by police in Cambrils.
Videotapes found alongside the images inside the hideout, also show one of the group saying: “Suffer. Enemies of Allah!”