Fifteen people, including children, have been killed in a suicide car bombing in Kabul.
The NATO-led International Security Assistance Force (ISAF) in Afghanistan said the attack targeted a military convoy.
U.S. and NATO officials said two American soldiers and four civilian contractors were among the dead.
An Afghan Health Ministry spokesman told RFE/RL's Radio Free Afghanistan that nine Afghan civilians were also killed and 39 others injured.
The militant group Hizb-e Islami, led by Gulbuddin Hekmatyar, has claimed responsibility.
President Hamid Karzai's office issued a statement condemning the attack "in the strongest terms."
The last significant attack in Kabul was on March 9, when a suicide bomber killed nine people outside the Defense Ministry during a visit by U.S. Defense Secretary Chuck Hagel.
With reporting by AFP, Reuters, and AP