At least two explosions and gunfire have rocked Istanbul's Ataturk international airport, with reports of "multiple" people injured. Two suicide bombers blew themselves up, Reuters news agency quoted a Turkish official as saying.
Police had opened fire to neutralise the suspects at an entry point, it added.
In December, a blast on the tarmac at a different Istanbul airport, Sabiha Gokcen, killed a cleaner.
Recent bomb attacks in Turkey have been linked to Kurdish separatists or the so-called Islamic State group.
Forty people were injured in the attack, Turkish newspaper Haberturk reports on its website (in Turkish).
Gunfire was reportedly directed from an airport car park.
A US State Department travel warning for Turkey, originally published in March and updated on Monday, urges US citizens to "exercise heightened vigilance and caution when visiting public access areas, especially those heavily frequented by tourists."
