Wim and Tobie were released onto the base proper on December 2. On Tuesday, they entered a hangar where several officers were gathered, according to the Associated Press:

The animals were shooed away, but as they stalked off, a warrant officer tried to take their picture. They began to growl. As the warrant officer turned to flee, they pounced.

Cheetahs do not usually attack humans because the animals prefer smaller prey. Captive-born cheetahs are familiar with human contact.

The cheetah natural-security program in South Africa began in July 1993, when two female cheetahs were brought to the Hoedspruit Air Force Base, according to a blog post on the website of Camp Jabulani, a private safari lodge located inside the Kapama Game Reserve in South Africa. The military post, located north of the reserve, saw frequent wildlife visitors, and the cheetahs’ presence made a difference.

Makhado was previously home to three other cheetahs. The animals are a better fit for the job than other big cats because “lions are very big and pose a greater threat to people, while leopards are skittish and would probably move away from the area in search of solitude,” explained the Hoedspruit center in a blog post last month. Male cheetahs are even better: “Female cheetahs are solitary animals. Should they make a kill around the airstrip, they will only consume half a carcass and subsequently lure vultures to the area, which can be an even bigger threat to incoming aircraft.”

Makhado spokeswoman Brigadier General Marthie Visser told the AP that Wim and Tobie will remain on the base. She said the military will investigate the “unprecedented incident,” and will do more to educate officers about cheetahs. The cats will serve a two-year tour at Makhado, and then return to the Hoedspruit center, which focuses on breeding cheetahs and eventually releasing them into the wild.

There are between 12,000 and 15,000 cheetahs left in the wild in Africa. The cheetah, the world’s fastest land mammal, is listed as “vulnerable” on the global inventory of threatened species; loss of habitat and prey, as well as hunting by farmers protecting their livestock, have contributed to declines in population.