The Islamic State group claimed responsibility for the attacks in Brussels, saying its extremists opened fire in the airport and "several of them" detonated suicide belts.
The posting in the group's Amaq news agency said another suicide attacker detonated in the metro.
The posting claimed the attack was in response to Belgium's support of the international coalition arrayed against it.
Florence Muls, a spokeswoman for the Brussels Airport, says a third bomb has been neutralized at the airport after two other bombs killed at least 10 people there Tuesday morning.
Muls told The Associated Press the third bomb was dispensed of "with a controlled action" once the chaos of the first explosives had eased somewhat.