The hunt for Europe’s most wanted man came to a sudden end in a hardscrabble Brussels neighborhood Friday afternoon when Belgian counterterrorism police raided an apartment building and came away with a suspect who could be the key to unlocking the mysteries of November’s massacre in Paris.

The success of the operation, after repeated failures to apprehend 26-year-old Salah Abdeslam, cheered European leaders and law enforcement officials, while offering the tantalizing prospect that authorities may soon uncover critical details of a terrorist plot that left 130 people dead on the streets of the French capital.

Abdeslam, who was shot in the leg during Friday’s arrest, was believed to be the last surviving direct participant in the Nov. 13 attacks and was considered the operation’s chief logistician.

Speaking at a news conference, French President François Hollande praised French and Belgian investigators and said that capturing Abdeslam alive “gives us the chance to know the whole truth.”

But he also acknowledged that the web of accomplices in the Paris plot may be far wider than has been previously known, and suggested that Friday’s raids would not be the final ones connected to the killings.

“We have to catch all of those who allowed or facilitated this attack,” Hollande said. “There are more of those people than we thought.”

Terrorism analysts said Friday’s arrests, which netted Abdeslam and four others, could mark a turning point in an investigation that has so far failed to unearth some of the most basic details of the Paris plot, including where it was hatched and by whom.

“It’s really crucial,” said Jean-Charles Brisard, chairman of the Paris-based Center for the Analysis of Terrorism. “Salah Abdeslam had a role in virtually every stage of the planning and the preparation. He could be the missing link to the masterminds.”

Abdeslam, a French national who grew up in Brussels and is of Moroccan heritage, visited Paris before the killings to scout out sites, and also leased cars, rented apartments and dropped off several attackers before they struck, investigators have said.

But instead of dying with several other attackers, including his older brother, he fled the scene, possibly after shedding a suicide vest. Investigators have theorized that he lost his nerve.

The Islamic State terrorist group claimed responsibility for the assault on civilian targets across the city — including a sports stadium, restaurants and a music hall featuring a concert by an American rock band — which left at least 368 people wounded in addition to those killed.

Law enforcement authorities came close to apprehending Abdeslam in the hours after the attacks, when French police stopped a car he was riding in near the Belgian border. But the officers, not realizing he was a suspect, allowed the car to proceed.

What we know so far about who carried out the Paris attacks

From then on, the search for his whereabouts was focused on Belgium, where authorities were so concerned that Abdeslam was planning a follow-up assault that they shut Brussels down for several days last autumn while conducting raids.

After months in which the investigation had seemed to go cold, the net tightened in recent days. Belgian federal prosecutors said that Abdeslam’s fingerprints were found in an apartment raided by police earlier this week.

On Tuesday in Brussels, a joint French-Belgian police operation had triggered clashes that left a suspect with possible Islamic State ties dead. Law enforcement identified the dead man as Mohamed Belkaid, a 35-year-old Algerian. Abdeslam may have narrowly escaped arrest that day.

But three days later, around 4:45 p.m., police closed in on him as he hid in an apartment block in Molenbeek, the Brussels neighborhood that he and others involved in the attack had called home.

Witnesses to the raid said they heard a fusillade of shots in the middle of a residential part of Molenbeek. Police “began shouting into a megaphone, telling a person to ‘put your hands in the air,’ ” a resident identified as Ilias told Belgium’s RTL television. “I didn’t understand what was happening. My son wouldn’t stop crying. We heard gunshots. It didn’t stop. A dozen gunshots. We saw a person on the ground.”

Broadcasters later aired video of security forces dragging a limping man with a hoodie over his head out of an apartment building and into a black Volkswagen police car. Hours after the initial raid, explosions were heard in a Brussels neighborhood where police searched for other suspected terrorists.

Of the four others arrested, three were members of Abdeslam’s family, who had sheltered him, a spokesman for the Belgian federal prosecutor’s office said. The fourth person, identified as Monir Ahmed al-Hadj, was wounded and transported to a hospital, the spokesman, Eric van der Sypt, told reporters in Brussels.

Following the arrests, President Obama called Hollande and Belgian Prime Minister Charles Michel to congratulate them.

Obama “commended the work of Belgian security services and noted that this significant arrest was the result of hard work and close cooperation between Belgian and French law enforcement authorities,” the White House said in a statement.

Sitting beside Hollande later in the evening, Michel hailed the arrests as “a huge success in the battle against terrorism and against this awful negation of human life.”

Hollande said France would seek Abdeslam’s extradition, a request that Belgian officials suggested they would quickly honor.

But even as the leaders celebrated Friday’s arrest, officials acknowledged that deep-seated problems with homegrown extremists persist in both countries.

Belgian Interior Minister Jan Jambon said that “cleaning up Molenbeek,” which has earned a reputation as a hotbed of Islamist radicalism in Europe, is “still not finished.” He told Belgium’s RTBF broadcaster: “The jihadists must be neutralized, and not a single person more be radicalized.”

Friday’s raid took place on Molenbeek’s Rue des Quatre-Vents, less than four blocks from the area’s town hall. Abdeslam grew up in a modest residence across a cobbled square from the town hall, the seat of local authorities who have been criticized for doing little to monitor the growing radicalization in their midst.

The 5-foot-7-inch Abdeslam was unemployed, with a record of small-time crime. He was known to hang around a Molenbeek cafe owned by his older brother, Brahim, who detonated a suicide vest on the Boulevard Voltaire on the night of the attacks. Brahim was buried in Molenbeek on Thursday.

Another brother, Mohamed Abdeslam, told reporters after the Paris attacks that Salah Abdeslam was divorced and had no children. At the time, friends and relatives expressed astonishment that he could have been involved in mass murder.

“Salah is a Muslim who prays, had in the last couple of months stopped smoking and drinking, and goes to the mosque once in a while,” Mohamed told the French channel BFMTV. “He dressed normally, didn’t show any signs of him being radicalized. It is a frustration that our family lived together without noticing what was going on.”

Witte reported from London and Birnbaum from Moscow. William Branigin in Washington and Souad Mekhennet in Frankfurt, Germany, contributed to this report.

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