BRUSSELS, BELGIUM - MARCH 24: A visitor writes a message in chalk at a memorial at Place de la Bourse for victims of terrorist attacks two days earlier, on March 24, 2016 in Brussels, Belgium. Belgium is observing three days of national mourning after 31 people were killed in a twin suicide blast at Zaventem Airport and a further bomb attack at Maelbeek Metro Station. Two brothers are thought to have carried out the airport attack and an international manhunt is underway for a third suspect. The attacks came just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Adam Berry/Getty Images)
