Five people have been arrested in a four-hour police operation, including the most-wanted fugitive following the Paris attacks in November, Belgium's federal prosecutor says.
A spokesman for the prosecutor's office said in addition to Salah Abdeslam and another suspect linked to the Paris attacks, they were holding three other people, all of whom were members of the family that had sheltered Abdeslam.
Abdeslam was "slightly injured," a spokesman for Belgium's federal prosecution said.
Abdeslam had been taken to the hospital to get treatment for the injury to his leg, Thierry Werts told journalists in Brussels.
The broadcaster RTBF reported that Abdeslam was taken to the Saint-Pierre hospital in the south of the Belgian capital.
Television footage showed armed security forces dragging a man with a sack on his head out of a building and into a car.
"We got him," Belgian government minister Theo Francken said on Twitter.
Belgium Prime Minister Charles Michel described the capture of the 26-year-old French suspect and two others as "a very important result in the battle for democracy".
French President Francois Hollande said he was confident they had links to the Islamic State group which claimed the attacks that killed 130 people.
"The threat level is very high," said Hollande, who was in Brussels for an EU summit.
He added that it was now clear many more people had been involved in the Paris attacks on a sports stadium, bars and cafes and concert hall than had been realised.
Hollande said France wanted to extradite Abdeslam, who was born and raised in Brussels to a Moroccan immigrant family, and hoped he would yield more clarity about an operation mounted by IS in which all the known attackers died.
Several bursts of gunfire rang out earlier in the capital's Molenbeek area - Abdeslam's home neighbourhood and the scene of past investigations into the Paris attacks - and police officers surrounded an apartment block there from about 4pm.
Two explosions were heard after the arrest, though it was unclear whether they were part of a new operation or the clear-up.
About 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 IS plans and structures, his contacts in Europe and Syria and support networks and finance.
Hollande said he was sure Abdeslam, whose elder brother blew himself up at a Parisian cafe on November 13, had also been in the city that night and had helped plan the attack.
Belgian police had found fingerprints belonging to Abdeslam at the scene of an apartment raided on Tuesday, prosecutors said.