Spanish Police say the driver in Thursday’s van attack that killed 13 people in a tourist area of Barcelona may still be alive and on the run.
They are hunting for Moroccan-born Younes Abouyaaqoub, named by Spanish media as the suspected driver.
A man previously reported as the key suspect, Moussa Oukabir, 17, was one of five men killed by police after a later attack in Cambrils, West of Barcelona.
Police say the suspects had been planning more sophisticated attacks.
They said blasts on Wednesday in the town of Alcanar deprived plotters of bomb material so they carried out simpler attacks using vehicles.
Abouyaaqoub, 22, lived in the town of Ripoll to the north of Barcelona.
Three people were arrested in Ripoll and one person in Alcanar on Friday.
Oukabir had previously been seen as the main suspect – but late on Friday police Chief Josep Trapero told local TV that the theory that he was the driver now “Had Less Weight”.
El Pais newspaper said there was a growing belief that Abouyaacoub was the main suspect.
Oukabir is suspected of using his brother’s documents to rent the van used in the Barcelona attack and another found hours later in the town of VIC, North of Barcelona, that was intended as a getaway vehicle.
In the early hours of Friday police shot dead five attackers including Oukabir in Cambrils after they drove a car into pedestrians killing one woman and injuring six others.
Police Chief Trapero said one officer killed four of the attackers single-handedly.
Police have named three of the five attackers in Cambrils – said Aallaa, 18, Mohamed Hychami, 24, and Oukabir.
Oukabir’s Brother Driss was among the three people arrested in Ripoll. He reportedly turned himself in, telling police he was not involved and that his documents had been stolen.
Thursday’s attack occurred when a fiat van was driven down the Pedestrianised Las Ramblas area on Thursday afternoon, killing 13 and injured scores more people.
The Islamic State (IS) group said it had carried out the attacks, though it is not clear whether the attackers were directly connected to the group or simply inspired by it.