A huge explosion at Bagram airbase in Afghanistan, the largest US military facility in the country, has killed at least four people.
At least 14 others were wounded in the blast, local district governor Haji Shookor told the BBC.
The Taliban said one of their suicide bombers had carried out the attack, which reportedly hit a dining area.
The base, near Kabul, has come under frequent attack, as the Taliban step up operations before the onset of winter.
The attack is a serious security breach of one of the best fortified military compounds in Afghanistan.
Bagram was hit while people gathered to celebrate Veteran's Day.
General John W Nicholson, US Army commander in Afghanistan, said in a statement:
''[To] the family and friends of those wounded in today's attack, let me assure you they are receiving the best care possible, and we will keep them in our thoughts today."
He said the incident was being investigated but did not disclose the nationalities of the casualties.
Taliban spokesman Zabihullah Mujahid said the blast had inflicted "heavy casualties on US invaders".
The attack on Bagram comes just a day after the German consulate in the city of Mazar-e-Sharif in northern Afghanistan was hit by a Taliban suicide bomb blast that killed six civilians and wounded some 120 others.
The Taliban said on Friday the attacks were carried out in retaliation for a recent coalition airstrike in Kunduz which reportedly killed some 30 civilians.
Last December, a Taliban suicide bomber riding a motorbike killed six US soldiers in a village near Bagram in one of last year's deadliest attacks on foreign troops.