The situation for rhinos is now so dire that one zoo is taking the drastic step of cutting the horns off its 18 rhinos to keep them safe.

A Czech zoo will anesthetize the animals and use a chainsaw to remove their horns, the Guardian reported. “It’s for the sake of rhino safety,” Andrea Jirousova, spokeswoman for the Dvur Kralove zoo said.

The zoo’s decision follows a break-in at a French zoo last week that resulted in the death of one of the facility’s white rhinos, five-year-old Vince. One horn was hacked off and the other was partially cut off. The incident is believed to be the first time a rhino has been killed at a zoo.

“The attack [in France] put us on the alert—the danger is really intense,” Jirousova said.

Rhino horns are in demand in Vietnam and China, where they’re made into valuable carvings and erroneously used as a cure-all in traditional medicine. Last year, poachers slaughtered 1,054 rhinos in South Africa, home to about 70 percent of the world’s remaining 29,500 rhinos. (Read more: Inside the Deadly Rhino Horn Trade)

It’s illegal to kill rhinos, and selling their horns between countries has been banned since 1977 under the Convention on International Trade in Endangered Species of Fauna and Flora (CITES), the 183-government body that regulates the global wildlife trade.

Yet for poachers the reward is often worth the risk of getting caught. On the black market in South Africa, the horn of a white rhino—of which some 21,000 remain in the wild—sells for up to $3,000 a pound, but on Asian black markets it wholesales for five to 10 times that. Retail prices increase from there.

Dvur Kralove now has a mix of 21 southern white rhinos and black rhinos, which are critically endangered. The herd includes three calves, who will not undergo the surgery, the Guardian reported.

“This incident shows how security is increasingly important for zoos in Europe, as well as for conservationists working in rhino range states,” Katherine Johnston, spokesperson for London-based Save the Rhino International, told National Geographic after the poaching at France’s Thoiry Zoo on March 7.

Rhino owners and conservationists in Africa have already taken the extreme step of de-horning their animals to ward off poachers. Rhino horns grow back.

Save the Rhino International says that rhinos use their horns, made mostly from keratin (which our fingernails are made of), to defend their territories and to protect calves from other rhinos and predators. But dehorning has also been shown to reduce fighting-related deaths among some rhinos.