When Ibrahim El Bakraoui blew himself up in the Brussels Airport check-in area, killing and maiming scores of travellers, it was at least the third time he had passed unimpeded through an airport terminal in recent months.

Belgium's interior minister and justice minister tried to resign Thursday ahead of an emergency meeting of European security chiefs held amid growing questions about why authorities couldn't prevent deadly Islamic extremist attacks on Brussels.

Belgian authorities continued to hunt for one of three suspects officials believe are responsible for the deadly attacks at an airport and subway station in Belgium’s capital city on Tuesday.