The lions had killed eight goats, each worth about $60.
Wednesday's killings highlight the growing threat to Kenya's wildlife posed by the rapid expansion of its capital. A week earlier, residents from another village on Nairobi's outskirts killed a leopard that had eaten a goat. Last month, wildlife service agents shot and killed a lion moving around the Nairobi suburb of Karen. On Thursday, three lions attacked and killed three goats outside Nairobi National Park. Rangers chased the lions back to the park.
Earlier this week, the Kenya Wildlife Service sent out a public notice pleading with people who encounter wild animals "to desist from killing them."
It summed up the problem in a posting on its Facebook page: "Do animals invade human space, or do humans invade animal space? How can we find tolerance for our wild neighbors? And how can we humanely remove them when they get a bit too close?"
As Nairobi enjoys a boom in apartment and road construction, an expanding population center is putting heavy pressure on the animals, especially big cats. Nairobi National Park is the only wildlife park in the world that lies in a country's capital.
Killing lions is a crime in Kenya, but those who lose livestock to big cats frequently retaliate. About 100 lions are killed each year, and the country's lion population has dropped to about 2,000. Lions, especially ones who leave Nairobi National Park, which is not completely fenced in, are at risk. After Wednesday's killings, the park had 37 left, KWS estimates.
As Nairobi continues to grow, small towns that cropped up on its outskirts expand, fueled by the demand for low-cost housing from the city's working class.
People are settling in traditional migratory corridors that wildlife from Nairobi's park have long used to access the plains to the south around Tanzania's Mount Kilimanjaro, or to travel to Kenya's Maasai Mara in the country's southwest, said Peter M. Ngau, a professor in the department of urban and regional planning at the University of Nairobi.
The herbivores migrate from the park in search of pasture during the dry season and the carnivores follow, KWS official Ann Kahihia said. "Unfortunately the carnivores do not know the difference between livestock and wild animals. Once they get livestock they just kill them," Kahihia said.
KWS Director Julius Kipngetich says the human population in the Kitengela area, where the six lions were killed, was low in the 1990s but has grown dramatically since the opening of an export processing zone there.
Even the annual migration of the wildebeests from Nairobi National Park to the Athi plains to Nairobi's east has been squeezed by human settlement, he said.
If parliament approves, the Kenyan government will start compensating people whose livestock are maimed or killed as an incentive to spare the attacking animals. KWS spokesman Paul Udoto said the government stopped compensation for wildlife attacks in 1987 after the program was abused.