The tribute has become a somber ritual following a string of high-profile attacks, including bombings in Paris last November, in Belgium in March and the Orlando nightclub shooting earlier this month.

The landmark building said it would darken its world-famous lights in sympathy for the victims and those affected by Tuesday''s attack.

Turkey and the CIA have pointed the finger of blame at the Islamic State extremist group based in Iraq and Syria. There has been no claim of responsibility.

Witnesses described scenes of terror and panic as the attackers began shooting indiscriminately and then blew themselves up at the entrance to Ataturk airport, one of Europe''s busiest aviation hubs.