Three adult black rhinos have been shot at the Imire Safari park in Zimbabwe.
Armed men in camouflage shot dead all three adult females
The park, 100km southeast of Harare, is home to one of the only breeding centres for the iconic animals.
The shooting has brought the local breeding programme - for what is one of the most endangered mammals on Earth - to a standstill.
Charles Hamilton has just returned to the UK from Zimbabwe, where his family runs the park. He called the situation "desperate".
He had tears in his eyes as he showed images of the dead animals on his laptop to BBC News.
The pictures showed all three of his family's adult black rhinos, lying dead on the dusty floor. You can see the bullet-holes in their thick hides. "It's just totally unbelievable," Charles sighed.
For the past 20 years the family has been rearing the animals and returning them to the wild, but last week, in the dead of night, armed men in camouflage gear burst onto the site and shot dead all three adult females.
One of them was just days away from giving birth. Her unborn calf died as well.
"We simply can't believe it. Those rhinos were our friends. We knew them all so well," said Charles.
"It is deeply tragic. We've been left with four little orphan rhinos, which won't be able to reproduce for about 20 years. The whole breeding programme is now at a standstill. It's desperate."
There are only about 3,000 black rhinos left in the wild, and the species is listed as Critically Endangered by the World Conservation Union, which means they "face an extremely high risk of extinction". Last year, one of the four sub-species was declared as "already extinct".
Not surprisingly, the shootings have caused deep alarm among conservation groups, not least because there have been a number of similar attacks in Zimbabwe this year.
Cathy Dean from Save the Rhino International said: "The situation for rhinos in the country is becoming more and more difficult every day. We must continue to support those working to save the vital rhino populations in this troubled nation."
So, who was responsible for the attack? And why would they have shot the black rhinos?
BBC News is banned from Zimbabwe but a government spokesman has told us that poachers are to blame. He described the shootings as "wanton destruction" and said the police and military had stepped up patrols to search for the gunmen.
Black rhinos are sometimes shot by poachers, who sell their horns as dagger-handles or for use in Chinese medicine, but the Imire rhinos had recently been de-horned as a precaution, so they didn't have any value to hunters.
This has led to fears that black rhinos are instead becoming a target in Zimbabwe's battles over land-ownership.
Cathy Dean from Save the Rhino said: "Over the last few years, we have made some real progress, working with the conservation authorities in Zimbabwe.
The youngest of the orphans is now being bottle-fed
"I hope this event, and others recently, don't mean we are returning to the disastrous poaching of the late 80s and early 90s. I hope this is not the start of a very worrying trend."
According to Charles Hamilton, the orphaned rhinos on his ranch have been left "stunned" by the deaths of their mothers.
The youngest of the orphans, baby Tamba, is now being fed by bottle.
"It's heart-breaking," says Charles, "but we are determined to give these animals a future, and the breeding programme will continue."