Spanish authorities pressed their search Saturday for the supposed ringleader of an extremist cell that carried out vehicle attacks in Barcelona and the seaside resort of Cambrils, as they looked into links among the Moroccan cell members.
Early in the morning, police searched two buses in northwest Catalonia in the hunt for any remaining members of the cell. Nothing was found in the searches in Girona and Garrigas, police tweeted.
Police also announced a series of controlled explosions Saturday in the town of Alcanar, south of Barcelona, where the carnage was planned in a rental house destroyed a day before the attacks by an apparently accidental blast.
Authorities had initially written off the Wednesday night incident as a household gas accident, but took another look on Friday and returned on Saturday.
Police believe the Wednesday night blast, which killed at least one person and injured one of the people currently in custody, actually prevented a far deadlier attack using explosives, forcing the extremists to use more "rudimentary" vehicles instead.
In a tweet Saturday, Catalan police urged Alcanar residents not to be alarmed by the controlled explosions.
In the attacks that began Thursday afternoon, a white van swerved onto Barcelona's most famous boulevard, killing 13 people and injuring more than 100 many of them foreign tourists visiting the city during the peak of the summer season. A few hours later, five extremists began mowing down people along the boardwalk in Cambrils.
One woman died and five others were injured before police shot and killed all five attackers.
One of the main suspects in the attacks, Younes Abouyaaquoub, a 22-year-old Moroccan, was believed to be at large. His name figures on a list of four main suspects sought in the attack.
The list was issued throughout Spain and into France, a Spanish official and a French police official told The Associated Press.
The French official said Spain had flagged a rented van that was believed to have crossed the border to the north.
In addition to the five people killed in Cambrils, four people have been arrested as part of the investigation.
In the past 13 months, militants have used vehicles as weapons to kill nearly 130 people in France, Germany, Britain, Sweden and Spain.