Afghan and NATO troops targeted a group of Taliban fighters in southern Afghanistan, killing 17 militants and wounding six others, the Defense Ministry said Monday. Four police were killed separately in a militant ambush in central Ghazni province, a provincial official said. The joint force clashed with militants in the Marjah district of Helmand province Sunday, the ministry said in a statement. The troops recovered militants' weapons and ammunition and 132 pounds (60 kilograms) of drugs after the clash, it said. Southern Afghanistan is the center of the Taliban-led insurgency that this year has claimed more than 2,700 lives in Afghanistan, according to an Associated Press tally of figures provided by Afghan and Western officials.