Gen Zelmai Oryakhail, the provincial police chief, says that a Taliban suicide car bomber first targeted the checkpoint this evening, followed by other insurgents who opened fire.
He says the attack set off a shootout in which all nine of the attackers were killed after reinforcement arrived at the scene in Zurmat district.
Taliban spokesman Zabihullah Mujahid in a text message to media claimed responsibility for the attack.
Taliban insurgents have stepped up their attacks on Afghan soldiers and police in recent months.