Spanish police on Monday shot dead a man who could be Younes Abouyaaqoub, the suspected driver of a van that mowed down pedestrians in Barcelona, amid a massive manhunt for the Moroccan national described as dangerous and likely armed.
"They have shot dead a suspect who could be the perpetrator of the attack", a source close to the probe told AFP on condition of anonymity.
Regional police confirmed a man wearing what appeared to be a suicide belt had been killed in Subirats, a village about 60 kilometres (37 miles) away from Barcelona, without identifying the individual.
Bomb disposal units have been dispatched to the site.
Earlier on Monday, police had launched an appeal for information about the 22-year-old fugitive, believed to be the last remaining member of a 12-man cell suspected of plotting last week's deadly attacks.
The other suspects have been killed by police or detained after the vehicle rampages in Barcelona and the seaside resort of Cambrils. The Islamic State (IS) claimed responsibility for the assaults, believed to be its first in Spain.
Authorities on Monday raised the death toll to 15, confirming that Pau Perez, a 34-year-old man found stabbed to death in a Ford Focus outside Barcelona on Friday, was killed by Abouyaaqoub.
The police had fired at the car as it forced its way through a checkpoint shortly after the Barcelona carnage, and later found Perez in the vehicle.
Investigators believe the victim was the owner of the car, which was hijacked by Abouyaaqoub to make his getaway.
Describing Abouyaaqoub as around 1.8 metres (five feet, 11 inches) tall, police tweeted four photographs of the man with short black hair, including three pictures in which he was wearing a black and white striped T-shirt.
He is "dangerous and could be armed", police in Catalonia said.
Spanish authorities were also officially notifying European police of the identity of the suspect to enable the launch of a Europe-wide manhunt.