An attack on Istanbul’s Ataturk international airport has killed at least 36 people and nearly 150 others wounded. Three attackers began shooting inside and outside the terminal late on Tuesday and blew themselves up after police fired at them, officials say. Most those killed were Turkish and foreigners were also among the dead, a Turkish official said. Ataturk is Turkey’s largest airport and a major transport hub for travelers from around the world.

Turkish Prime Minister Binaldi Yildirim said early signs pointed to so-called Islamic State but no-one has so far admitted the attack. If ISIS is indeed behind this attack, as the U.S. and Turkey say, this would be a declaration of war. Turkey’s vengeance will come down like rain from hell. Thus far, Turkey has avoided engaging ISIS in full war, instead prioritizing its battle against Syria’s Assad regime as well as blocking advances by the Syrian Kurds. For Turkey, fighting ISIS as a first order battle could now be unavoidable.

Pictures from the airport terminal showed bodies covered in sheets, with glass and abandoned luggage littering the building. Turkish President Recep Tayyip Erdogan said the attack should serve as a turning point in the global fight against militant groups. “The bombs that exploded in Istanbul today could have gone off at any airport in any city around the world,” he said. The US called the attack “heinous”, saying America remained “steadfast in our support for Turkey”. German Interior Minister Thomas de Maiziere called the attacks “cowardly and brutal”.

This attack is going to hurt Turkey’s tourism economy and the business community by seriously challenging the idea that Turkey is a safe place to visit and do business. Istanbul’s Ataturk Airport is the main entry point for the majority of the more than 30 million people who visit Turkey every year. It’s also the hub of Turkish Airlines, the country’s only known international brand and the gateway to doing business in Istanbul.