Kabul, April 20 : Six armed militants were killed and 28 people were freed from a Taliban detention centre after the Afghan army launched a special operation in Helmand province, the Defence Ministry said on Tuesday. "The commandos of Afghan National Army launched the raid in surrounding areas of Helmand's Musa Qala district. A gunfight took place when the troops arrived at the targeted facility, and six armed militants were killed," Xinhua news agency quoted the Ministry as saying in a statement. The freed people received medical checkups after they were shifted to an army camp, according to the statement. Taliban insurgents frequently detain civilians and off-duty soldiers from villages and highways and punish civilians for spying for government security forces. The Taliban militant group has not made a comment on the report so far. /IANS