A suicide bomber kills at least 16 civilians, three foreign soldiers, and an interpreter in an attack at a security checkpoint in Afghanistan's city of Khost.

Khost is the provincial capital in the volatile eastern region bordering Pakistan. It is an operations base for the Taliban-linked Haqqani network, which the U.S. says has been behind a string of bombings in Kabul.

At least 30 people were wounded in the attack, including children.

Afghanistan is in the third phase of a five-stage transition in which the centers of provincial capitals, including in the violence-plagued south and east, will be handed-over to Afghan forces before the withdrawal of most foreign combat troops in 2014.

Deborah Lutterbeck, Reuters