BRUSSELS, Belgium (AFP) – Belgium yesterday said that two brothers with links to the Paris attacks were among the suicide bombers who struck Brussels, as mourners observed a minute’s silence for victims of the carnage.

Hundreds of people gathered in a historic city square applauding and chanting “We love Belgium” in an emotional tribute to the 31 people killed and 270 injured in Tuesday’s blasts at Brussels airport and a metro train.

Prosecutors identified Ibrahim El Bakraoui as one of two men who blew themselves up in the Zaventem airport departure hall while his brother Khalid struck at the Maalbeek metro station in the attacks on the symbolic heart of Europe.

Police stepped up a manhunt for a third airport assailant whose bomb failed to go off in the attacks claimed by the Islamic State group which have left European leaders once more grappling for ways to tackle the jihadist threat.

Belgian authorities had already been hunting the Bakraoui brothers, both Belgian nationals with long criminal records, over their links to Salah Abdeslam, the key suspect in the Paris massacre who was arrested in Brussels on Friday after four months on the run.

Federal prosecutor Frederic Van Leeuw revealed that airport bomber Ibrahim El Bakraoui had left a desperate “will” on a computer that he dumped in a trash can in which he said “I don’t know what to do.”

In an apparent reference to Abdeslam, Bakraoui added: “I don’t want to end up in a cell next to him.”

A third man in a hat and white jacket, seen on CCTV footage with Bakraoui and another unidentified suicide attacker pushing their bomb-filled bags through the departure hall shortly before the attacks, “is on the run,” Van Leeuw said.

Belgian media withdrew a report that a man arrested in the capital on Tuesday was Najim Laachraoui, another suspect whose DNA has been found on explosives linked to the Paris rampage.

Investigators found a virtual bomb factory in an apartment near where Ibrahim’s computer was left, during a raid in the Brussels district of Schaerbeek on Tuesday night, an area that has links to Abdeslam.

They found 15 kilos (33 pounds) of TATP high explosive, chemicals and detonators, Van Leeuw said. Prosecutors said on Tuesday an unexploded bomb, an IS flag and bomb-making materials had been found.

Three days of national mourning have been declared in a country deeply shocked by the bloodshed.

King Philippe, Prime Minister Charles Michel and European Commission chief Jean-Claude Juncker led a minute’s silence outside the EU headquarters in Brussels, the city that is also home to NATO.

In the city’s Place de la Bourse where mourners have laid banners and candles, defiant applause broke out among the large crowd gathered to honour the dead, chanting: “Long live Belgium”.