JAMBI, Indonesia (AP) — Two endangered Sumatran elephants were found dead in western Indonesia and authorities believe they were killed by poachers.

Krismanko Padang, head of nongovernment group of Indonesia Elephant Conservation Forum, said carcasses of 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 urged the police to thoroughly investigate to find the perpetrators or their masterminds.

He quoted villagers as saying a group of about 30 elephants had been wandering around the region in recent weeks.

In September, three elephants were found poisoned in Aceh in northern Sumatra.

Fewer than 3,000 Sumatran elephants are left in the wild. Environmentalists say they could be extinct within three decades unless they are protected.