On Tuesday, two explosions at the airport and one at a metro station left 31 dead and hundreds wounded.
Two other attackers at the airport have not yet been identified, however one died and the other is on the run.
Belgian and French media are suggesting that the wanted man is jihadist Najim Laachraoui.
Frederic van Leeuw, a Belgian prosecutor, has said that the brothers are known to the police with previous criminal records. DNA records identified them.
Prosecutors say Brahim left a note in a nearby rubbish bin: "I'm in a hurry. I don't know what to do anymore, they're looking for me everywhere. I'm not safe anymore. If I give myself up they'll put me in a cell."
The RTBF broadcaster has quoted a police source, which claims that the brothers rented a flat in the Forest area of the Belgian capital where police killed a gunman in a shootout last week.
During that raid, police found a fingerprint of Salah Abdeslam, who is the main suspect in the Paris terror attacks of November 13th 2015, as well as an Islamic State flag, according to the report.
We will bring you more updates as it happens.