Europe's most wanted man was captured after a shootout in Brussels in a major coup for authorities investigating November's Islamic State attacks on Paris.
Salah Abdeslam, 26, the first suspected active participant taken alive, was being held overnight in hospital with a slight leg wound, Belgian Prime Minister Charles Michel announced at a news conference alongside French President Francois Hollande.
"This is an important result in the battle for democracy," Michel said on Friday, adding that U.S. President Barack Obama had called to congratulate the Belgian and French leaders.
A Belgian minister broke the news by tweeting, "We got him."
Prosecutors said a second wanted man, who used the false name of Amine Choukri, was also wounded and captured in the raid on the apartment in Abdeslam's home neighborhood of Molenbeek.
The operation, planned after fingerprints and passports were found in a bloody raid three days earlier, was staged in a rush after media leaked word that police had found Abdeslam's trail.
Hollande, who was visiting Brussels for a European summit, confirmed France would seek extradition for the Brussels-based Frenchman who, he said, was definitely in Paris on the bloody night of Friday, Nov. 13 when 130 people were killed.
Abdeslam's elder brother, a Brussels barkeeper who shared a chequered history of drugs and petty crime, blew himself up outside a Parisian cafe that night. Hollande said the younger man's role in the killings was unclear but investigators were sure he helped plan the operation for the Syria-based group.
Since all the identified attackers were killed, Abdeslam offers France a major new chance to understand what happened.
It was now clear, Hollande said, that many more people had been involved in the Paris attacks on a sports stadium, bars and cafes and concert hall than was first thought. Security concerns remain, he added, "The threat level is very high."
Television footage showed armed security forces dragging a man with his head covered out of a building and into a car.
Several bursts of gunfire rang out earlier in Molenbeek, a down-at-heel borough that is home to many Muslim immigrants, notably of Moroccan descent like Abdeslam's family. Two explosions were heard after the arrest, though it was unclear whether they were part of a new operation or the clear-up.
A handout picture shows Belgian-born Abdeslam Salah seen on a call for witnesses notice released by the French Police Nationale information services on their twitter account November 15, 2015.
Some four hours later, the main police presence had stood down but crime scene investigators were still at work.
There had long been speculation about whether Abdeslam had stayed in Belgium or managed to flee to Syria.
Security services will be seeking information from Abdeslam on Islamic State plans and structures, his contacts in Europe and Syria and support networks and finance. Over the past four months, France and Belgium have detained several people linked to the prime suspects but none they suspect of a major role.
A man and two women, members of what prosecutors said was "the family which hid Abdeslam," were detained with the two wanted men and will be questioned. Investigators will want to know how extensive a network, under a code of silence, was able to hide such a high-profile fugitive in a busy inner city neighborhood just a few hundred yards from his parents' home.
Security agencies' difficulties in penetrating some Muslim communities, particularly in pursuit of Belgium's unusually high number of citizens fighting in Syria, has been a key factor in the inquiry, along with arms dealing in Brussels.
A four-month inquiry that had seemed to go cold, heated up this week when French and Belgium officers went to an apartment in the southern Brussels suburb of Forest on Tuesday, thinking they were simply looking for physical evidence in the case.
Instead, at least two people sprayed automatic gunfire at them as they opened the door, wounding three officers. An Algerian called Mohamed Belkaid was shot dead after a siege but two people were believed to have gotten away. Prosecutors said on Friday these may have been Abdeslam and the man called Choukri.
They also said the Algerian was wanted, under the false name Samir Bouzid, since he appeared on CCTV wiring cash to a woman just after the Paris attacks. She was a cousin of Abdelhamid Abbaoud, a Belgian who fought in Syria and is believed to have been a local organizer for Belgian and French militants. Abbaoud and his cousin died in a gunbattle in a Paris suburb on Nov. 18.
Crucially, police found Abdeslam's fingerprints.
They also found a fake Belgian ID card issued to "Choukri" and a fake Syrian passport for the same man in the name Monir Ahmed Alaaj. That man had been fingerprinted - as Choukri - by German police when he and Abdeslam were stopped in a car there in October. Those prints turned up again in January at a house used by the plotters in a small town south of Brussels.
Police at the scene of a security operation in the Brussels suburb of Molenbeek in Brussels, Belgium, March 18, 2016.
On Friday, local media said, a tapped telephone confirmed that Abdeslam was in the house in rue des Quatre-Vents (Four Winds Street) in Molenbeek. After French media broke word of Abdeslam's fingerprints being found in the Forest flat, police moved in within three hours and seized the pair in minutes.
After his elder brother Brahim blew himself up, Salah Abdeslam was driven back to Brussels from Paris overnight by two men who admitted doing so and are now in custody on terrorism charges, along with eight other suspects in Belgium.
French police stopped Abdeslam three times on the drive back but his details were circulated only after he reached Belgium.
The attack strained relations between Brussels and Paris, with French officials suggesting Belgium was lax in monitoring the activities of hundreds of militants returned from Syria.
Hollande and Michel took pains to exchange compliments to their security services and warm cross-border cooperation.
Among those still being sought is 31-year-old Belgian Mohamed Abrini, who was caught on CCTV with Abdeslam at a fuel station on the motorway to Paris two days before the Nov. 13 attacks.