The two brothers and one more suspect, believed to be Najim Laachraoui, 25, were caught on the airport CCTV before the explosions, with Laachraoui thought to be the one who planted the explosive charges, according to Belgian newspaper DH.

Reports now indicate that Brahim was the airport bomber, while Khalid was behind the subway attack.

According to local broadcaster RTBF, citing a police source, the apartment raided by the police last week in the Forest borough of Brussels was rented by Khalid El Bakroui under a false name. The raid last week found weapons and an Islamic State (IS, formerly ISIS) flag, as well as fingerprints belonging to key suspect Salah Abdeslam, who was detained three days later.

According to RTBF, the link to terrorism was only made by the Belgian police in the wake of the Brussels attacks, despite the two brothers being on the radar for some time. The Bakraoui brothers also had criminal records for violent crime. Brahim was sentenced in 2010 for firing a Kalashnikov at police officers in the course of an armed robbery. He was released before serving his full sentence.

Earlier on Tuesday the police got a major break in the case when a taxi driver, who had unwittingly driven the three suspects to the Brussels airport, came forward with information.

The driver had recognized the trio after driving them to the airport early in the morning, HLN reports. He recalled them trying to fit too much luggage into the car, more than it could take. They were forced as a result to leave some bags behind, something they were visibly angry about. He tried to help them with the load, but was ordered not to touch anything.

Police raided the address where the suspects had been picked up, in Schaerbeek, finding the remaining suitcases, which contained an IS flag, nail bombs and hazardous chemicals.

Hours after the raid police were still at the property. A helicopter was reportedly seen hovering over the suspects’ address, with a sniper at the ready, as a large group of masked Belgian police worked the scene.

A subsequent airport search yielded two more unexploded devices, which were destroyed by police.

Armed raids have been taking place across the capital in the wake of the airport and Metro attacks that claimed more than 30 lives and injured 250 people.