The police on Friday shot Moussa Oukabir, the suspected driver of a van which killed 13 people in Barcelona.
The 17-year-old is reported to have used documents belonging to his brother, Driss Oukabir, to rent the van that ran into crowds of pedestrians in the Las Ramblas district.
13 were killed and more than 100 were injured in the attack, that was claimed by the Islamic State group.
The second attack was launched on Thursday night in the town of Cambrils, just over 70 miles south of Barcelona.
Police said that the same cell was responsible for the assault.
Four of the suspects were earlier shot dead by the police.
Investigators found an axe and knives inside the car, indicating that the men were planning a stabbing rampage.
The other suspects reported to have been killed are Said Aallaa and Mohamed Hychami. However, another suspect, Younes Abouyaaqoub, remains at large.
