“There was an explosion at Bagram Airfield this morning. There have been casualties,” Xinhua news agency cited a statement as saying.
The nature of the blast and further details about the incident remain unknown, it said.
Our force protection and medical teams are responding to the situation, the statement read.
The Bagram Airfield, around 50 km north of Kabul, has been serving as a main US military base in Afghanistan over the past 15 years.
More than 13,000 NATO-led Resolute Support mission, with majority of them Americans, are stationed in Afghanistan following the end of the combat mission of the alliance forces in the war-torn country in late 2014.