KABUL, Afghanistan (AP) -- A security firm has confirmed that four civilian contractors killed in a suicide car bombing in Afghanistan were Americans.
Thursday's bombing in Kabul also killed two American soldiers and nine Afghan civilians, including two children.
DynCorp International says four of its employees were working with U.S. forces training the Afghan military when the blast occurred.
An Islamic militant group, Hizb-e-Islami, claimed responsibility for the attack, saying it had stalked the convoy for weeks.
It was the bloodiest attack in the Afghan capital since March 9, when suicide bombers struck while U.S. Secretary of Defense Chuck Hagel was visiting.