At least 15 people were killed and 35 wounded in Kabul by a suicide bomber who attacked a military convoy in the Afghan capital.
Kabul Police Chief General Salangi said a Toyota Corolla was blown up beside the military vehicles at about 8am on Thursday.
Two US soldiers and four civilian contractors were among the dead. Nine Afghan civilians were also reported to have died. Several houses were destroyed and a wide area of the city is cordoned off.
It was the first major blast in Kabul since March, when a suicide bomber blew himself up near the defence ministry, killing nine people.
The Hezb-e-Islami group told the BBC it was responsible. Hezb-e-Islami is based in north-eastern Afghanistan and is led by the former prime minister Gulbuddin Hekmatyar.
The Taliban said in April it would target foreign military bases and diplomatic areas in a new offensive.
Most international troops are due to leave Afghanistan by the end of 2014.