Belgian police have arrested a suspect amid an extensive manhunt, a day after a series of bombings, claimed by the DAESH terrorist group, ripped through Brussels airport and a metro train, killing at least 31 people.
Media sources originally said the suspect detained in the city's Anderlecht District was 25-year-old Najim Laachraoui, who is believed to have been seen on CCTV fleeing the scene of the first bombing.
However, it was later reported that the person detained was not Laachraoui.
Two blasts carried out by suicide attackers hit the check-in hall at Zaventem Airport on Tuesday morning around an hour before another bomb exploded at the Maelbeek metro station in the heart of the city's EU quarter, just as commuters were making their way to work.
At least 11 people had been killed at the airport, while Brussels Mayor Yvan Mayeur said "around 20" died in the metro.
Among the hundreds wounded in the two attacks were four US Mormon missionaries, two Britons, eight French and two Colombians.
Belgian authorities released pictures of two of the suspected attackers pushing trolleys through the terminal and said that they were "actively searching" for a third suspect whose bomb failed to go off.
"They came in a taxi with their suitcases, their bombs were in their bags," Zaventem Mayor, Francis Vermeiren, said. "They put their suitcases on trolleys, the first two bombs exploded. The third also put his on a trolley, but he must have panicked, it didn't explode."
Two of the bombers were identified on Wednesday morning as Belgian brothers Ibrahim and Khalid el Bakraoui. According to the Belgian public broadcaster, RTBF, the bombers were previously known to the police.
Police helicopters hovered over the city late into the night and raids were under way across Belgium, prosecutors said, adding that a bomb, a DAESH flag and chemicals had been found in an apartment.
The attack came just four days after the arrest of Salah Abdeslam in Brussels, who had been on the run for four months after escaping Paris, having participated in the Nov. 13 attacks that left 130 people dead.
Abdeslam was arrested three days after evading a capture in a shootout in southern Brussels last Tuesday that saw an Algerian DAESH-linked terrorist killed.
Investigators believe Abdeslam slipped out of the apartment as the gun battle erupted. He was finally captured in Brussels' Molenbeek District - just around the corner from his family home.
Belgian authorities had been on alert after Abdeslam told investigators that he had been planning an attack on Brussels.
Brussels is the headquarters of both NATO and the European Union.
Life began to return to normal in Brussels on Wednesday, with some public transport working and cars returning to the European district, but the metro system remained closed and the airport was still shut to travellers.
Belgians gradually began to arrive at the bombed sites to lay flowers and mourn the victims of what could be considered as one of the worst tragedies to hit the country in its recent history.
"This is a day of tragedy, a black day," Belgian Prime Minister Charles Michel said. He also announced three days of national mourning after the "deadliest attacks we have ever seen in Belgium."
Belgian King Philippe also condemned the "cowardly and odious" assault.