The attack was carried out around 8 p.m. on Monday, when a terrorist tried to make his way into an Afghan Local Police (ALP) camp in Babar Tangai area of Chawkay district, Xinhua news agency reported.
The ALP personnel intercepted the bomber, but the attacker detonated his explosive, causing the casualties, provincial government spokesman Ghani Musamim said.
No group has claimed responsibility for the attack so far, but Taliban militants and Islamic State fighters have presence in the mountainous province.
The government established the ALP, or community police, in 2010 to protect villages and districts around the country where army and police have limited presence.
The Afghan security forces’ casualties have risen since the beginning of 2015 when Afghan soldiers and police assumed full responsibilities of security from the US and NATO troops.