One of the world's rarest tigers was killed this week after being caught in a pig trap on the Indonesian island of Sumatra, Agence France Presse reported, citing local officials.

What's worse, the critically endangered Sumatran tiger was pregnant with two cubs when it died and was expected to give birth in two weeks, local reports said.

The death is a major setback to the species, as fewer than 400 Sumatran tigers currently exist, according to WWF estimates.

The tigress was seen Tuesday caught in a pig trap set by a hunter in Muara Lembu village in the Riau province, AFP said. Officers immediately traveled to the site but found that the animal was missing.

The following day, officers searched the area again and found the tiger dead near a ravine with a wire from the trap wrapped around its body.

A necropsy showed that the wire had ruptured the animal's kidney and led to its death, The Jakarta Post reported. The tiger was approximately 3.5 to 5 years old.

Authorities said Thursday they arrested a man—identified only as "E"—in connection with the tiger's death. He said he used the traps to catch pigs and denied killing the tiger intentionally.

"He admitted that he had set up several traps in various areas," the head of the Riau Natural Resources Conservation Agency told The Jakarta Post. "I told E that he was supposed to wait around the trap to prevent other animals from being harmed if he actually wanted to catch a pig. If a tiger passed by, then he should shoo it away. What would happen if it was his kid instead who was trapped?"

If convicted, E could face 5 years in prison and a Rp 100 million (US$6,708) fine under Indonesian law, The Jakarta Post said.

There are roughly 3,890 tigers remaining in the wild, according to WWF. As EcoWatch previously mentioned, threats faced by these iconic big cats include poaching for their pelts, illegal rainforest destruction for palm oil production and habitat loss due to climate change, such as coastal erosion due to sea level rise.