SUBIRATS, Spain — The fugitive believed to have driven the van in last week’s terrorist attacks in Spain was shot to death by the police Monday in a village outside Barcelona after a search across Europe, police said.

Younes Abouyaaqoub, 22, allegedly used a van to mow down a crowd on Las Ramblas, Barcelona’s central boulevard, on Thursday. He was the last remaining fugitive from the Spanish cell that carried out the Barcelona rampage and another vehicle attack in nearly Cambrils, investigators said.

The death toll from the twin attacks rose to 15 on Monday. In addition to the 13 people killed in Barcelona, a 14th person died hours later in Cambrils. On Monday, police announced a 15th victim: the driver of the car that Abouyaaqoub stole and used to make his escape.

Investigators said Abouyaaqoub stole a car, killed its driver, and made his getaway with the driver’s body still inside.

After four days on the run, Abouyaaqoub was spotted outside a train station in Subirats, about 33 miles west of Barcelona, on Monday afternoon. A witness told police she was certain she had seen the man whose photo has gone around the world as part of an international search, the Associated Press reported

He was shot to death after he flashed what turned out to be a fake suicide belt at two troopers who confronted him and cried out ‘‘Allah is great’’ in Arabic, said Major Josep Lluís Trapero, the Catalan police chief.

Police said they had evidence that Abouyaaqoub drove the van that barreled through the Barcelona promenade.

Investigators have said Abouyaaqoub’s brother and friends made up the rest of the 12-man extremist cell, along with an imam who police said died in a botched bomb-making operation.

A search extending across Europe was undertaken after the rampage, and France, Italy, and other countries tightened security and border controls amid widespread speculation that Abouyaaqoub might have fled Spain. Over the weekend, authorities had said they could not be certain that he was still on Spanish soil.

But at 4:10 p.m. Monday, attention quickly turned to Subirats. The town was placed on lockdown as authorities announced that a man wearing an explosive belt had been “shot down.’’

The identity of the suspect was not clear for about two hours; a robot, operated by a police bomb squad, was going through the explosive device to ensure that there was no danger. But at 6:20 p.m., police announced that the man who had been shot was indeed Abouyaaqoub.

Residents of Subirats appeared frightened but unharmed.

“They told us to keep inside, to be ready for anything,’’ Pere Pons, the mayor of Subirats, told Catalan radio. “A little while ago the police called us to stay in our houses. To keep calm, to wait for more police to arrive.’’

He added: “The entire town is surrounded by police.’’

The police operation was continuing, however, amid reports that the fugitive may have had an accomplice during his flight and that police were inspecting an abandoned van. Authorities in Sant Sadurní, another town west of Barcelona, issued a message on Twitter warning residents of a police intervention and urging them to remain calm.

The attacks were Spain’s deadliest terrorist assault since 2004, when terrorists bombed commuter trains in Madrid, killing 192 people.

Also Monday, authorities said that an imam believed to have inspired the twin attacks had almost certainly died Wednesday when a house that the terrorists used as a bomb factory blew up — an event that appears to have precipitated the attacks.

The imam, Abdelbaki Essati, preached in the town of Ripoll, home to many of the members of the terrorist cell, which the authorities say included at least 12 people.

Investigators believe the planning for the plot may have begun not long after Essati’s arrival, a year ago, at the second of two mosques where he worked in Ripoll.

Abouyaaqoub fled on foot from Las Ramblas, police said, and crossed another popular tourist destination, La Boqueria, a busy food market. He then spotted a stationary car in the city’s university district, killed the owner, and put the body on the back seat. Then he forced his way through a police checkpoint.

The driver, Pau Pérez, was found stabbed to death in his vehicle on the outskirts of Barcelona.

Two of the 15 people killed were children, including a 7-year-old who had Australian and British citizenship.