UNITED NEWS INTERNATIONAL (UNI) — Poachers used cyanide to kill four elephants at a national park in Zimbabwe.

Zimbabwe Parks and Wildlife Management Authority spokesman Tinashe Farawo said the dead elephants were found  Jan. 25 with their tusks removed.

The incident happened in Hwange National Park, located in the western Zimbabwe.

Farawo said more and more poachers are using poison rather than loud guns, so they don’t alert patrolling rangers.

This isn’t the first case of cyanide poisoning at the national park.

Last year, 10 elephants were poisoned and had their tusks removed.

Local media reports the government said it is ramping up efforts to protect the animals, which includes imposing harsher punishments for poaching and raising awareness through educational campaigns.

Demand for ivory has led to rampant elephant poaching in recent years, decimating the population.

Poachers kill roughly 20,000 to 30,000 elephants every year.