ARMED men yesterday killed at least six rangers and wounded several others in an ambush in eastern Democratic Republic of Congo's Virunga National Park, a sanctuary for endangered mountain gorillas, the park said. The identity of the assailants was not immediately clear, said Olivier Mukisya, a Virunga spokesman. Previous attacks against the rangers have been blamed on various militias who fight to control land and natural resources in eastern Congo. "We confirm this sad news. A group of armed men attacked our positions in the region of Nyamitwitwi in the middle of Virunga National Park," Mukisya told Reuters. More than…