The perpetrators of the terror attacks in Barcelona and Cambrils originally planned to use explosive devices to wreak greater devastation but were apparently thwarted because their materials detonated prematurely, police said Friday.
A house in Alcanar, south of Barcelona, was destroyed in a blast Wednesday night -- hours before one attacker mowed down dozens of people in the heart of Barcelona, killing 13. A group of five attackers then drove into pedestrians in the town of Cambrils, killing one, in the early hours of Friday.
Catalan police chief Jose Lluis Trapero told reporters that explosives were found in the Alcanar property and that police "are working on the hypothesis that these attacks were being prepared in that house."
The explosion meant the attackers were unable to use material they were planning to deploy in attacks in Barcelona, Cambrils and perhaps elsewhere, he said. The attack in Barcelona was therefore "more rudimentary than they originally planned," Trapero said.
The revelations pointed to an alarming conclusion: that a highly organized terror cell had gone undetected until their explosives accidentally blew up the house where they were based -- and despite the setback they still managed to carry out two further improvised attacks without impediment.
-- Four people have been arrested: one of them in Alcanar and three in Ripoll. Three were Moroccan citizens and another was Spanish and ranged in age from 21 to 34. None was on the radar for terrorism.
-- People from at least 34 countries are among the injured in the attacks, Catalan authorities said. US Secretary of State Rex Tillerson said an American citizen was among the dead. The first to be identified was an Italian.
-- Spain's Prime Minister Mariano Rajoy labeled the Barcelona attack "jihadi terrorism." Rajoy's government has declared three days of mourning across Spain.
-- Rajoy, the Catalan regional president Carles Puigdemont and other officials held a crisis cabinet meeting in Barcelona.