Moroccan-born Moussa Oukabir, 17, Said Aallaa, 18, Mohamed Hychami, 24, and Younes Abouyaaqoub, 22.
The suspects in the attacks in Barcelona and Cambrils were planning one or more bigger attacks than those that were carried out, police say.
They said blasts on Wednesday in a town south of Barcelona deprived plotters of bomb material, so they executed simpler attacks using vehicles to ram crowds.
Oukabir is suspected of carrying out Thursday’s attack on Barcelona’s Ramblas. Scores of others were injured as a van driver zig-zagged along the famous tourist street.
Moussa Oukabir, a Spanish citizen from the northern Catalan city of Girona, is suspected of using his brother’s documents to rent the van that mowed down people on the famous boulevard.
Hours later, police killed five suspected jihadists in a second vehicle attack in the town of Cambrils. Police said the men killed in Cambrils were linked to the Barcelona attack, which the Islamic State (IS) group said it had carried out.
Spanish media, quoting unnamed police sources, said Oukabir was among those killed in Cambrils but there has been no official confirmation.
Spanish Prime Minister Mariano Rajoy has condemned what he called a „jihadist attack” in Barcelona. He has announced three days of national mourning and a minute’s silence was held at noon (10:00 GMT) on Friday.
Police say they are investigating the theory that the attacks were being prepared over a substantial period of time in a private house in Alcanar, a small town south of Barcelona.
Explosions ripped through a building on Wednesday evening, apparently caused by exploding gas canisters. The explosives were being prepared for use in one or more attacks in Barcelona, police said.
Catalan Police Chief Josep Lluis Trapero said the actual attacks in Barcelona and Cambrils were „rudimentary” by comparison.
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