Poachers broke into a French zoo overnight Monday, killing a 4-year-old southern white rhinoceros and stealing one of its horns in the first known instance of deadly poaching on zoo land in Europe, according to the Zoological Park of Thoiry.

A caretaker found the rhino, named Vince, on Tuesday morning in the zoo’s African Plains exhibit. Two other rhinos housed at the zoo, 37-year-old Gracie and 5-year-old Bruno, were not injured.

“We are all affected, especially the caretaker who has made this macabre discovery,” the zoo’s founder, Paul de La Panouse, told France’s Le Parisien newspaper. “One gets attached to these animals, especially the big ones, and we cry when they leave us, especially under these circumstances.”

The poachers, who have not been identified, broke into the zoo through a gate near the African Plains exhibit. They headed to the rhinoceros building, where they forced their way through a pair of doors and into the animal lodges, zoo officials said.

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The poachers shot Vince three times in the head and cut off one of the rhino’s horns with what authorities believe to be a chainsaw. Vince’s second horn was partially cut but not taken, indicating that the poachers were interrupted or that they had “defective equipment,” according to zoo officials.

“This odious act was carried out even though there were five staff members living onsite and security cameras,” the zoo said in a statement.

Vince was born in late 2012 at Bergers’ zoo in Arnhelm in the Netherlands. He moved to the Thoiry zoo in 2015 and is part of the “extremely endangered” southern white rhinoceros subspecies.

“It’s extremely shocking,” Duguet told France’s 20 Minutes newspaper. “An act of such extreme violence has never happened before in Europe.”

Zoo officials said thefts of rhinoceros horns are on the rise across Europe. Trafficking in wild species and things taken from them, like rhino horns, is severely punished under French law.

A single rhinoceros horn is estimated to fetch between $31,000 and $43,000, according to The Guardian. Authorities told the newspaper that a trade network specializing in poached horns stretches between France and Asia, where the horns are in demand because of their supposed aphrodisiac properties.

The Thoiry zoo, just outside Paris, is famed for its safari park, which can only be explored from the inside of a vehicle, according to The Associated Press.

Poachers break into a French zoo and kill an endangered rhinoceros for its horn (Parc Zoologique de Thoiry)