Afghan police say a suicide car bomber has targeted a convoy of foreign military vehicles in the capital.
The number of dead and wounded in the Thursday morning blast in Kabul was not clear.
NATO's International Security Assistance Force said it was aware of the explosion and was looking into reports of casualties.
Taliban militants have been ramping up attacks on government forces lately, seeking to destabilize Afghanistan as more foreign troops prepare to draw down from the 12-year war.
The number of dead and wounded in the Thursday morning blast in Kabul was not clear.
NATO's International Security Assistance Force said it was aware of the explosion and was looking into reports of casualties.
Taliban militants have been ramping up attacks on government forces lately, seeking to destabilize Afghanistan as more foreign troops prepare to draw down from the 12-year war.