None of the four suspects detained in connection with the Spain attacks had a background in terrorism, a senior Spanish police official has said.
The detained men are three Moroccans and a Spaniard.
A manhunt for the driver of the van in the Barcelona attack is still under way. He has still not been identified, police say.
Two men charged with murder and membership of a terror organisation as judge orders a fourth suspect to be freed on bail.
Younes Abouyaaqoub was wearing a fake bomb vest when he was killed in the town of Subirats, about 30 miles west of Barcelona.
The man believed to be responsible for driving a van into pedestrians in Barcelona has been pictured as the death toll rises to 15.