They were forced to retreat after an hour of fighting. Some four insurgents and four police officers were killed in the battle.
Afghan police said the insurgents attacked the city of Bakwa, in the Farah Province, late on September 13.
It is the third major attack in the province in three days.
RFE/RL Afghanistan Report
SUBSCRIBE For regular news and analysis on Afghanistan by e-mail, subscribe to "RFE/RL Afghanistan Report."