Two brothers involved in the attacks were named earlier
Several people possibly linked to the terror attacks at Brussels Airport and a metro station are still at large, say federal prosecutors.
Frederic Van Leeuw identified two of the attackers as brothers Ibrahim and Khalid El Bakraoui but said others involved have not yet been caught.
He did not identify two of the three men caught on airport CCTV moments before the explosives were detonated.
The third man was pictured on the airport CCTV wearing a hat alongside two other bombers - Ibrahim El Bakraoui and a second suspect, who killed themselves and at least a dozen others in the attacks.
The twin blasts ripped through the airport's departure hall but the third suspect was reported to have fled the scene after his bomb failed to detonate.
Investigators were tipped off by a taxi driver who had driven three "suspicious" individuals to the airport - and was told not to touch their luggage upon arrival.
He directed police to the house in the Brussels suburb of Schaerbeek, where he had picked them up.
Inside the property detectives found a nail bomb, chemical products and an Islamic State flag.
Erdine lives opposite the apartment - and says he thinks he saw the suspects getting into the cab:
Najim Laachraoui (25) had been named in Belgian media reports as the third man filmed on CCTV at the airport - but Mr van Leeuw did not confirm this when he spoke to a press conference on Wednesday.
"The third man is on the run; he left his bag with the biggest bomb in it which exploded later because it was so unstable," Mr van Leeuw said, referring to the man in a hat and white coat in the CCTV images.
"This third person remains unidentified and is still being looked for".
Laachraoui, previously known as Soufiane Kayal, is also suspected of making the bombs used in November's Paris massacres, after his DNA was allegedly found on suicide belts used in the Bataclan Theatre and the Stade de France.
Prosecutors had said on Monday - the day before the Brussels attacks - that he had travelled to Hungary in September with Salah Abdeslam, the prime suspect in the Paris attacks, who was captured by police last week.
Laachraoui, born and raised in Brussels, is also believed to have travelled to Syria in February 2013.
Meanwhile, more detail has emerged on Ibrahim El Bakraoui, one of two men who blew themselves up at the airport, and his brother Khalid, 27, who carried out a suicide attack from inside a train carriage at Maalbeek metro station.
The brothers had criminal records but had not previously been linked by police to terrorism, it was reported.
Ibrahim had been sentenced to nine years in prison after being convicted in October 2010 of firing a Kalashnikov assault rifle at police and wounding an officer after a robbery in Brussels earlier that year.
In 2011, his brother Khalid was jailed for five years for car jacking.
Mr van Leeuw also said Ibrahim's will was found on a computer after the attacks, quoting from it as he said: "Always on the run, not knowing what to do anymore, being looked for everywhere, not being safe any longer and that if he waits around any longer he risks ending up next to the person in a cell".
Meanwhile, Turkey's president has revealed one of the Brussels airport bombers was handed over to Belgian authorities in June - and then released.