A 15th victim was killed when one of the attackers made his getaway.
Six of the attackers shot dead by police, five on Friday and one Monday, were wearing fake suicide belts.
Chief investigating magistrate Fernando Andreu provisionally jailed two of the four surviving alleged cell members yesterday after hearing testimony in the National Court in Madrid that the group had been preparing the massive bombs for an imam who planned to blow himself up at a Barcelona monument.
The two, Mohamed Houli Chemlal, 21, and Driss Oukabir, 28 identified Es Satty as the ideological leader of the cell according to a Spanish judicial official who attended the proceeding and briefed journalists but wasn't authorized by the court to be identified in news reports.
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Houli Chemlal was arrested in a hospital after surviving the blast. He told the court he was alive because he was on the outside porch of the house washing dishes after dinner.
Police had already found at the house more than 100 tanks of butane gas, nails that they planned to use as shrapnel, and 500 liters of acetone, a highly flammable liquid necessary to make TATP, an explosive used by Islamic State group militants.
Vilafranca is 15 kilometers (nine miles) from where Younes Abouyaaqoub, the suspected driver in the Barcelona attack that killed 13 people, was shot dead Monday by police.
Abouyaaqoub, who fatally stabbed another person while fleeing Thursday, is known to have changed clothes, picked up a bag of knives and a fake explosive belt in the time between the Barcelona attack and his death.
Another member of the cell abandoned that afternoon another rented van involved in an accident in a highway near Cambrils, a coastal town south of Barcelona.