Three suicide bombers blew themselves up at Istanbul's Ataturk international airport killing 31 people and injuring 147, Turkish officials said.
The attacks took place Tuesday evening local time, near a security check at the entrance to the arrivals terminal. There were reports of explosions and gunfire, according to witnesses at the airport, one of the busiest in the region.
All planes were being diverted to nearby airports, an official said. Among the dead and injured were foreign nationals, according to the official.
Turkish President Recep Tayyip Erdogan condemned the "terrorist attack," saying "innocent civilians" were the victims. In a statement following a top level security meeting, he said such an "heinous" attack could occur at any airport in the world.
"We urged the world, especially Western countries, to take a firm stance against terrorism," he said, vowing to keep up the fight against terrorism.
US State Department had issued a warning of "increased threats" in Turkey on Monday. US media outlets cited US officials saying Islamic State was a key suspect.
The US has grounded all flights to and from Istanbul, and President Barack Obama was briefed, according to the White House, which condemned the "heinous terrorist attack," while recalling the attack on the Brussels airport this year.
The wounded were ferried to nearby hospitals, with a large number of ambulances dispatched.
Following the attack people were trying to exit the chaotic scene at the airport, while television footage showed hundreds of others waiting outside. Later crowds began forming outside hospitals.
Roads to the airport were backed up significantly.
Condemnation statements were coming in from around the world, including one from UN secretary-general Ban Ki-moon, who said through a spokesman that he hoped "the perpetrators of this crime will be identified and brought to justice."
Police at the airport opened fire near the security check on two suspects, who then blew themselves up, an official said based on initial information.
Turkish Justice Minister Bekir Bozag, who provided the death toll, said one of the attackers opened fire with an assault rifle and there were also signs of an explosion near the metro station at the airport.
Videos on social media showed panicked passengers and sounds of gunshots, along with explosions and other activity inside the building. The footage could not be independently verified.
Ataturk has security checks with X-ray machines and metal detectors both at the entrance to the terminal, before the check-in counters, and again by passport control
As usual in such incidents, Turkish authorities have imposed a partial broadcast and media ban.
Three weeks ago, 11 people were killed in an attack near Istanbul's historic Grand Bazaar three weeks ago.
That attack, claimed by the Kurdistan Freedom Falcons (TAK), followed two suicide bombings that hit tourist-heavy areas of Istanbul this year, blamed on Islamic State.
In December, Sabiha Gokcen airport in Istanbul was hit by mortar fire claimed by TAK killing at least one staff member.