Six people have been arrested in raids connected to attacks on Brussels that killed 31 people and injured 270 other people Tuesday.

According to authorities, the arrests took place in the city's Schaerbeek and Jette districts on Thursday. Officials did not immediately identify those arrested or say what roles they allegedly played in the bombings.

During raids around Brussels earlier this week, prosecutors found "a large stash of explosives and other bomb-making material," in an apartment in Schaerbeek believed to have been used by the suicide bombers, the Associated Press reported.

On Tuesday, two bombs were detonated at Brussels Airport. Roughly an hour later, a third blast rocked the Maelbeek Metro station.

Prosecutors have identified three of the suspects: brothers Ibrahim and Khalid El Bakraoui and suspected ISIS bomb-maker Najim Laachraoui. All three are dead. Two more suspects remain on the loose.