The Taliban claimed responsibility for an explosion at the NATO air base at Bagram, north of the Afghan capital Kabul, on Saturday which local officials said killed at least four people and wounded 14 others.
The NATO-led Resolute Support mission said an explosion occurred just after 5.30 a.m. and that there had been casualties.
It said force protection and medical teams were responding.
The Taliban's spokesman, Zabihullah Mujahid, claimed responsibility for the attack in a message on his Twitter account.