Mohamed Belkaid, a 35-year-old suspect who was armed with an assault rifle, was killed by a police sniper after a tense standoff in the Belgian capital yesterday afternoon.
He was described by authorities this morning as an Algerian national who was in the country illegally.
His body was found next to the black and white flag of ISIS, an extremist terror manual and a store of ammunition.
Belgian federal prosecutors said officers found a Kalashnikov rifle in a building on the same street as the initial police raid.
Police in Brussels hunting terror suspects linked to last November's ISIS massacre in Paris earlier detained two men after a dramatic raid on an apartment in which the Algerian accomplice was killed and four officers were wounded.
All three of those arrested or killed are thought to have links to the deadly ISIS-inspired attacks on the French capital, which left 130 dead.
At a press conference this morning, the prosecutor said one of the detained men had been arrested after arriving at a Brussels hospital with a broken leg.
Brothers Khalid and Ibrahim El Bakraoui, who were named in Belgian media, are believed to be the two men detained after fleeing the scene yesterday afternoon.
The men are reportedly known for their links with violent crime in the Brussels area.
Brussels went into lockdown for several days after the Paris attacks as authorities feared another major incident there.
Several of those involved in the ISIS shootings and suicide bombings were based in the city.
Belgian prime minister Charles Michel has summoned security and intelligence chiefs for an emergency sitting of Belgium's national security council.
One or more people opened fire on police as they opened a door of an apartment. One of the wounded, none of whom was in a serious condition, was a French policewoman.