There are reports of as many as 40 people injured after casualties were rushed to hospital in taxis.
Two suicide bombers blew themselves up, Reuters news agency quoted a Turkish official as saying.
Police opened fire to stop the suspects at an entry point.
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.