A Taliban spokesman, Yousuf Ahmadi, said his organization carried out the attack.
On Tuesday, another suicide attacker blew up a car bomb inside a district police compound in southwestern Nimroz province, killing two policemen and wounding five.
In eastern Kunar province, a truck supplying fuel to Nato troops hit a roadside bomb that killed the Afghan driver on Thursday, a statement from Nato's International Security Assistance Force (Isaf) said.
No Nato service members were hurt in that attack.