Catalan Police spokesman Albert Oliva later said a manhunt is still underway for any remaining members of the Islamist cell, with the search focused on a 22-year-old Moroccan called Younes Abouyaaqoub.
Spain mounted a sweeping anti-terror operation on Friday after a suspected militant drove a van into crowds in Barcelona, killing 13 people before fleeing, in what police suspect was one of multiple planned attacks.
The terror cell behind Spain's deadly twin attacks has been "dismantled", interior minister Juan Ignacio Zoido said on Saturday, although local authorities took a more cautious tone.
Numerous suspects from this week's attacks were caught or killed in the town Cambrils, around 70 miles from Barcelona, where they launched their second assault, injuring five.
Spain will maintain its security alert at four, one notch below the maximum level which would signal an attack was imminent, Zoido said on Saturday.
A total of 14 people were killed in the twin terror attacks - 13 in Barcelona and one in Cambrils, where a auto was driven into a crowd of pedestrians before police shot and killed the five suspects after they left the vehicle.
Spanish media reported that Abouyaaqoub was the driver of the van in Barcelona.
In addition to the five people killed in Cambrils, police said they arrested two people Friday, after two arrests a day earlier.
Two brothers have been named in reports about the search for the perpetrators: Moussa Oukabir, a dual citizen of Morocco and Spain who was being sought by police along with three others Friday, and his older brother Driss Oukabir, who was arrested on Thursday. "Police shot and killed all five of these men, and they were wearing fake explosive vests".
The blast was followed by yet another explosion on Thursday that killed one person and injured more than 10 people working at the scene.
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Four of the five suspected terrorists were killed by a single police officer, the Mossos police of Catalonia said Friday.
One person each from Hungary, Macedonia, Austria and Turkey was injured.
Ben Wallace, the United Kingdom security minister, said the terror threat to Britain was rising as Islamic State loses battles and territory in Syria and Iraq.
British Prime Minister Theresa May said in a televised address that "a number of British nationals were caught up in the attack", but provided no other details on the number of wounded.
Both attacks followed the same modus operandi with drivers deliberately targeting pedestrians in the latest in a series of such assaults in Europe. The explosion killed two members of the jihadist cell, police say.
"The explosion in Alcanar stopped larger attacks from happening because they no longer had some of the material they needed", Trapero said.
He also said Spanish authorities considered the cell behind the attacks had been fully dismantled.
The attack unfolded when an Audi A3 containing the five suspects ran down a number of pedestrians before crashing into a police vehicle and overturning.
Unlike France, Britain, Sweden and Germany, Spain has largely been spared, thanks in part to a crackdown that has netted about 200 suspected jihadis in recent years.