Pacha Gul Bakhtyar, security officer of the police headquarters of Helmand province says that the attack took place yesterday afternoon.
He said that suicide attacker who was driving a vehicle laden with explosives targeted a security check post in Haidar Abad area of Gerishk district leaving one policeman killed and six others wounded.
Taliban have claimed responsibility for the attack.
This was second explosion in the country yesterday.
The first explosion took place in Logar province after a civilian vehicle ran over a landmine leaving all seven passengers of the vehicle killed including children and women.