Gunmen wearing army uniforms stormed the compound in the Balkh province, killing dozens of soldiers, Afghan government officials said Friday.
A Taliban attack on a mosque and a dining facility today at Camp Shaheen outside Mazar-e-Sharif in Afghanistan has killed "probably more than 50" friendly Afghan forces and civilians, a U.S.
Mr Thomas said it was unclear how close US-led coalition troops were to the fighting.
Waziri said five attackers were killed in the battle, including one wearing a suicide vest who was killed by soldiers before he could trigger his explosives.
At least one armed man continues to resist, he said, with another killed and a third arrested.
A Taliban spokesman, Zabihullah Mujahid, said the attack began with a suicide vehicle bombing, making way for other assailants to enter the 209 Shaheen Corp military headquarters.
Two years ago, Taliban fighters shocked US and Afghan commanders in Kabul by briefly capturing Mazar-e-Sharif, Balkh's provincial capital and the country's third-largest city. They went straight to the mosque where ANA soldiers were praying, and opened fire.
Last week, American bombers dropped the so-called "mother of all bombs" on a Islamic State tunnel complex in the Achin district in eastern Afghanistan's Nangarhar province.
US-led North Atlantic Treaty Organisation troops have been at war in Afghanistan since 2001, after the ousting of the Taliban regime for refusing to hand over Osama bin Laden following the 9/11 attacks in the United States. "Nor were any other soldiers in the multinational force harmed", said a spokesman for the German Operations Command.