Officials at Democratic Republic of Congo's Virunga National Park say the Monday slayings of six staff members is the deadliest known ambush of its kind in the park's history.In a statement on Tuesday, Virunga officials blamed Mai Mai militia members for the attack that killed five rangers and a park driver. Another ranger was injured.Virunga is home to about one-fourth of the remaining mountain gorillas in the world, and the work of protecting them has proven dangerous. Monday's deaths bring the number of rangers killed on the job since the vast park in far east DRC which was established in 1925 to 175, officials said.Poachers target the gorillas, but their habitat is also being destroyed by deforestation to produce charcoal. Human rights groups say armed groups are active in the charcoal industry.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.