Two of the men who carried out attacks in Brussels on Tuesday have been named by Belgian media as the brothers Khalid and Brahim el-Bakraoui.
The RTBF broadcaster said the pair were known to police. It is believed at least one was among three suspects seen in a CCTV image at Zaventem airport.
Twin explosions at the airport and another at a metro station on Tuesday left about 34 dead and 250 wounded.
Belgium is observing three days of national mourning.
So-called Islamic State (IS) has said it was behind the attacks and warned that more would follow.
Meanwhile, the suspect still at large has been named as Najim Laachraoui, who was already being sought by police after he was linked to the Paris attacks in November, Reuters reports Belgian newspaper DH as saying.
On Monday, prosecutors said his DNA was found in houses used by the Paris attackers last year. He was also said to have travelled to Hungary in September with Paris attacks suspect Salah Abdeslam. (BBC)