UNITED STATES.- Eight critically endangered black rhinos are dead in Kenya after wildlife workers moved them from the capital to a new national park, the government said Friday, calling the toll “unprecedented” in more than a decade of such transfers.

Preliminary investigations point to salt poisoning as the rhinos tried to adapt to saltier water in their new home, the Ministry of Tourism and Wildlife said in a statement, describing how the animals likely became dehydrated and drank more salty water in a fatal cycle.

The ministry suspended the ongoing move of rhinos and said the surviving ones in the new park were being closely monitored.

The loss is “a complete disaster,” said prominent Kenyan conservationist Paula Kahumbu of WildlifeDirect.

Conservationists in Africa have been working hard to protect the black rhino sub-species from poachers targeting them for their horns to supply an illegal Asian market.

In moving a group of 11 rhinos to the newly created Tsavo East National Park from Nairobi last month, the Kenya Wildlife Service said it hoped to boost the population there. The government agency has not said how the rhinos died. Fourteen of the animals were to be moved in all.