KHOST (Agencies) - Up to 13 civilians, mostly women and children, were killed in a Nato air strike on Thursday in the eastern Afghan province of Khost, provincial police chief Mohamad Zazai said. The coalition said those killed were family members of insurgents who also died in the strike that was called in after Afghan-led forces came under fire. The deaths triggered protests blocking the main highway to Kabul nearby, with civilian casualties in Western military operations extremely sensitive in war-torn Afghanistan, where the Taliban have waged a decade-long insurgency. Unfortunately eight women, four children, and one man were killed in a Nato air strike on a residential house in Dowamanda district early this morning, Zazai said, adding that four Taliban-linked Haqqani militants were also killed. The body of a Haqqani commander and three fighters have also been recovered from the vicinity of the house. A delegation has been sent to investigate the incident, he said. A spokesman for the provincial governor confirmed that civilians had been killed in the incident but gave no further details. Natos International Security Assistance Force said those killed were family members of the Haqqani network, which is a target of the alliance force. It did not say how many civilians were among the dead. A spokesman for the coalition said Afghan-led forces had gone in search of the insurgents when they came under attack by rocket-propelled grenades and small-arms fire. Responding to the insurgent attack, the security forces returned fire and called in an air weapons team. The subsequent air strike killed several insurgents and unintentionally a number of associated family members, he said. The air strike came a day after provincial authorities in southern Ghazni province said two civilians were killed and one other injured in another military incident. Nato said it was looking into the allegations. Police said eight Afghan policemen were killed late Thursday when their vehicle struck a mine in northern Afghanistan. The incident took place in northern Jawzjan province as the men were on their way to the provincial capital Shibirghan, provincial deputy police chief Mohammad Ebrahim told AFP. Eight of our policemen were killed at around 2 oclock this afternoon when their vehicle hit a roadside mine in Fayz Abad district, he said. Meanwhile, a Nato helicopter crashed Thursday in eastern Afghanistan but no one was hurt, the US-led coalition said.