https://phys.org/news/2018-07-endangered-black-rhino-dies-kenya.html

Police detectives have now been brought in and given one week to determine what caused the deaths, said Tourism Minister Najib Balala at a briefing in Nairobi.

"Nine of them died due to reasons we are still investigating. The preliminary report that we got from the experts from Kenya Wildlife Service was saying it's the saline water" they drank, he added.