At least 15 policemen have died in a helicopter crash in Antiquita province due to a technical failure.Fifteen policemen aboard were killed and two injured in the crash in a jungle area of the province, police said.The police officers were part of a special operation to tackle down criminal gangs operating in the area, including the most feared "Usaga Clan", Xinhua reported."We express heartfelt condolences to the families of these brave men who gave their lives fighting organised crime, and offers a permanent accompaniment to overcome this difficult time," the police statement said.