The head of the Indonesia Elephant Conservation Forum, Krismanko Padang, said carcasses the two male elephants were discovered early this week near a palm oil plantation in the Tebo district of Jambi province on Sumatra island.
Their skulls were found without tusks, Krismanko said late Wednesday. He added that police who are investigating discovered some bullet shells near the scene.
He quoted villagers as saying a group of about 30 elephants had been wandering around the region in recent weeks.
Fewer than 3,000 Sumatran elephants are left in the wild. Environmentalists say they could be extinct within three decades unless they are protected.