Four members of the rare and endangered mountain gorilla species were killed in Uganda by a lightning strike. The Greater Virunga Transboundary Collaboration (CVTC) conservation group reported Saturday that the animals had “gross lesions” consistent with electrocution.

Post-mortem tests are being done on the bodies to confirm the causes of death.

Three of the gorillas were adult females, while the remaining one was an infant male. One of the females was also said to be pregnant. Only a little over 1,000 mountain gorillas are currently alive.

“This was extremely sad," Andrew Seguya, executive secretary of the GVTC, said in a statement to the BBC. “The potential of the three females for their contribution to the population was immense”

The animals were found dead in the Mgahinga National Park in Uganda, one of the species' protected areas. Other protected areas are located in the Democratic Republic of Congo and Rwanda.

The deceased gorillas were said to be part of the “Hirwa family,” a group of mountain gorillas in the park that had 17 members. Seguya confirmed that the surviving members of the group have been found and are doing well.

The work of conservation groups like the GVTC is largely credited with the change in status for mountain gorillas in 2018 from “Critically Endangered” to “Endangered.”

A member of the Humba family of mountain gorillas at Virunga National Park in Eastern Democratic Republic of Congo. April Simpson