JOHANNESBURG (AP) — South African authorities say they are searching for five lions believed to be roaming since last week in the country’s most populous province.

Drew Abrahamson, founder of conservation group Captured in Africa, said Monday that she and colleagues were contacted Friday by police in Fochville, about 60 kilometers (37 miles) southwest of Johannesburg, South Africa’s biggest city.

Abrahamson says police spotted the lions while investigating an animal carcass. She speculates that the lions were owned illegally because any legal owner would likely have notified authorities of missing predators.

Abrahamson says a small plane is searching for the lions.

The incident in Gauteng province is unusual because much of the area is developed. In July, South African officials shot and killed three lions that escaped from the country’s Kruger National Park.