An international manhunt was underway Saturday for the driver of a van that killed 13 people in Barcelona, as police probed the wreckage of a suspected bomb factory for clues to the cell behind two terror attacks in Spain.
The flattened ruins of a house in the village of Alcanar have become the center of a massive police investigation into a terror cell suspected of using the house to make bombs.
When an explosion destroyed the house Wednesday night, killing one person and seriously injuring another -- now arrested on suspicion of involvement in the attacks -- it set in train a series of events culminating in the deaths in Barcelona and one more in a second attack in the town of Cambrils.
A massive manhunt has been underway since a van plowed into pedestrians in the heart of Barcelona on Thursday afternoon, killing 13 and injuring 120.
Hours later, a group of five attackers drove into pedestrians in the town of Cambrils, killing one and injuring six, in the early hours of Friday. Police shot dead the five attackers, who they said were armed with knives, axes and fake explosive belts.
Police said late Friday that it is "increasingly unlikely" that the driver in the Barcelona attack was among the suspects shot dead in Cambrils, the Reuters news agency reported.
A Catalan police spokesman on Saturday confirmed the names of three of the five suspects killed in Cambrils as Moussa Oukabir, Said Aallaa and Mohamed Hychami.
He also said that Younes Abouyaaqoub, who's wanted in connection with the attack in Barcelona, remains on the run. Spanish media report that Abouyaaqoub is a 22-year-old Moroccan national.
Four people have been arrested, three in the town of Ripoll, to the north of Barcelona, and one in the village of Alcanar.
Authorities believe the terror cell involved in the Barcelona and Cambrils attacks -- believed to number about 12 -- has been "completely dismantled," Spanish Interior Minister Juan Ignacio Zoida said at a news conference Saturday.
"[This is] the conclusion we reached today in our meeting on the terror alert," he said. "Everyone agreed that we can say that the terrorist cell in Barcelona has been completely dismantled when you consider those who are dead, those who have been arrested, and those who have been identified but that we cannot discuss because they are subject to an ongoing investigation."
Bulldozer clears rubble in Alcanar
Now the ruins of the house in Alcanar, a quiet beach town about 125 miles south of Barcelona, may hold the key to unraveling the plans and methods of that cell.
Police suspect the property was being used as a base to make explosives that could have been used in even more devastating attacks in Barcelona, Cambrils and possibly elsewhere, had they not blown up prematurely.
Explosives experts brought in a bulldozer Saturday to clear the rubble in Alcanar, as police warned residents to expect more blasts from controlled explosions. "If you hear detonations DO NOT be alarmed," the force tweeted.
Three explosions had been heard as of 2 p.m. local time.
Alcanar's vice-mayor, Jordi Bort, told CNN that the house, in the town's Montecarlo area, belonged to a bank and had been illegally squatted by the group without its knowledge.
The town is home to a mix of yearlong residents and some who just spend their holidays or weekends here, he said. The neighbors did not suspect any wrongdoing at the property.
The septic tank of the house, which had only one floor, was being used as storage for the tanks and explosives, Bort said.
Police said Friday there were other "biological remains" found at the site, but it is unclear whether they belong to a different person.
Source: Traces of TATP found
Catalan police chief Josep Lluis Trapero on Friday told reporters that Wednesday's explosion meant the attackers were unable to use material they were planning to deploy in attacks.
The attack in Barcelona, capital of the Spanish region of Catalonia, was therefore "more rudimentary than they originally planned," Trapero said.
Saturday's controlled explosions may help authorities to understand what materials and methods were involved in their planning.
Trapero said the suspects in the Alcanar house had been trying to "make explosives out of butane gas among other things."
A source briefed on the investigation said a preliminary assessment of the Alcanar property indicated there were traces of the powerful explosive TATP in the rubble.
TATP is made by adding an acid to a mixture of acetone and hydrogen peroxide solution and can easily result in accidental detonation if mistakes are made in preparation.
TATP was used in the November 2015 Paris attacks, the March 2016 Brussels bombings, the Manchester bombing in May and a failed bomb attempt by an Islamist extremist at the Gare Centrale in Brussels in June.
Many Islamist terrorists who have successfully made TATP have received some form of terrorist training.
ISIS issued a formal claim of responsibility for the two attacks on Saturday. However, the extremist group did not provide any proof it carried out the attack nor provide the names of the attackers nor their number. There are also inconsistencies between the ISIS statement and the police version of events.
The ISIS media wing, Amaq, earlier said the Barcelona attackers were "soldiers of the Islamic State," but stopped short of explicitly claiming responsibility for the attacks or providing evidence for their claims.
Crowds show defiance, solidarity
In Barcelona, crowds returned to Las Ramblas on Saturday morning and street vendors were once again selling drinks and ice cream from kiosks on the Plaça de Catalunya, close to where Thursday's attack started.
Plenty of tourists could be seen, although there was still an obvious police presence at the entrances to metro stations.
Security measures are being enhanced in areas where there are large crowds of people, Zoida, the interior minister, said Saturday, before adding that there does not appear to be an immediate threat of another attack.
Spain's threat level will remain at Level 4 following the terror attacks, one level down from the maximum, Zoida said.
King Felipe, the Spanish head of state, was expected to visit injured survivors of the attack in two hospitals on Saturday.