BARCELONA, Spain (AP) — Spanish police put up scores of roadblocks across the northeast as the manhunt continued Sunday for the suspected driver of the van that plowed into pedestrians in Barcelona.

Police in Catalonia are searching for Younes Abouyaaquoub, a 22-year-old Moroccan suspected of carrying out the attack Thursday in Barcelona that left 13 dead and over 120 people wounded.

The investigation is also focusing on a missing imam who police think could have died in a massive house explosion Wednesday. Police believe imam Abdelbaki Es Satty radicalized the young men in the extremist cell, which may have accidently blown up a house in the quiet seaside town of Alcanar with the explosive material it was collecting. Es Satty in June abruptly quit working at a mosque in Ripoll and has not been seen since.

His former mosque denounced the deadly attacks and weeping relatives marched into a Ripoll square on Saturday, tearfully denying any knowledge of the radical plans of their sons and brothers. Abouyaaquoub’s mother says his younger brother Hussein has also disappeared, as has the younger brother of one of five radicals slain Friday by police during an attack on the resort of Cambrils that left one pedestrian dead.

Authorities said the two attacks were the work of a large terrorist cell that had been plotting for a long time from a house they took over in Alcanar. The Islamic State group has claimed responsibility for both attacks.

On Sunday, Spain’s king and queen and its prime minister attended a solemn Mass at Barcelona’s Sagrada Familia Basilica for the victims of the terror attacks.

King Felipe VI and Queen Letizia were accompanied by Spanish Prime Minister Mariano Rajoy, Catalan regional President Carles Puigdemont and other officials at the Mass celebrated by the Archbishop of Barcelona, Cardinal Joan Josep Omella.

Everyone so far known in the cell grew up in Ripoll, a town in the Catalan foothills 100 kilometers (62 miles) north of Barcelona. Spanish police searched nine homes in Ripoll, including Es Satty’s, and set up roadblocks. French police carried out extra border checks on people coming in from Spain.

Neighbors, family and the mayor of Ripoll said they were shocked by news of the alleged involvement of the young men, whom all described as integrated Spanish and Catalan speakers.

Halima Hychami, the weeping mother of Mohamed Hychami, one of the attackers named by police, said he told her he was leaving on vacation and would return Aug. 25. His younger brother, Omar, slept in late Thursday, left mid-afternoon and has not been heard from since. Mohamed Hychami is believed among the five extremists killed in Cambrils.

“We found out by watching TV, same as all of you. They never talked about the imam. They were normal boys. They took care of me, booked my flight when I went on vacation. They all had jobs. They didn’t steal. Never had a problem with me or anybody else. I can’t understand it,” she said.

Even with Abouyaaquoub and others at large, Spanish Interior Minister Juan Ignacio Zoido declared the cell “broken” Saturday. In addition to the five killed by police, four were in custody and others were killed in a house explosion Wednesday. He said there was no new imminent threat of attack.

Police conducted controlled explosions Saturday in Alcanar, south of Barcelona.

Initially, only one person was believed killed in the Wednesday blast that destroyed a house in Alcanar. But officials said DNA tests were underway to determine if human remains found there Friday were from a second victim. A police official, speaking on condition of anonymity to discuss the ongoing searches, said investigators believed they may belong to Es Satty.

The official said investigators also discovered ingredients of the explosive TATP, used by the Islamic State group in attacks in Paris and Brussels, as well as multiple butane tanks.

Neighbors on Saturday said they had seen three vehicles coming and going from the home, including an Audi used in the Cambrils attack and the van used in the Barcelona attack.

The president of the mosque where Es Satty preached, Ali Yassine, said he hadn’t seen him since June, when he announced he was returning to Morocco for three months.

“He left the same way he came,” said a bitter Wafa Marsi, a friend to many of the attackers, who appeared Saturday alongside their families to denounce terrorism.

Fatima Abouyaaquoub, sister-in-law of the Hychami brothers and the cousin of Younes Abouyaaquoub, found it all hard to believe.

“I’m still waiting for all of it to be a lie. I don’t know if they were brainwashed or they gave them some type of medication or what. I can’t explain it,” she said.

Islamic extremists have made a point of targeting Europe’s major tourist attractions — especially in rented or hijacked vehicles. But in the last two years, the extremist group has steadily lost ground in its self-declared caliphate in Iraq and Syria.

By late Saturday, the Catalan emergency service said 53 attack victims still remained hospitalized, 13 of them in critical condition.

The 14 people killed spanned generations — from age 3 to age 80 — and left behind devastated loved ones. They included a grandmother, 74, and her granddaughter, 20, from Portugal who were visiting Barcelona to celebrate a birthday; an Italian father who saved his children’s lives but lost his own; an American man who was celebrating his first wedding anniversary.

Francisco Lopez Rodriguez, a 57-year-old Spaniard, was killed with his 3-year-old grand-nephew, Javier Martinez, while walking along the Las Ramblas promenade. His widow Roser is recovering in a hospital.

“We are a broken family,” niece Raquel Baron Lopez posted on Twitter.

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Hinnant and Oller reported from Ripoll. Angela Charlton in Paris; Nicole Winfield in Rome; Mystyslav Chernov in Ripoll; Oleg Cetinic in Alcanar; and Ciaran Giles in Madrid contributed.