Story highlights Flooded park in northeastern India is home to 70% of species' population

Ten rhino calves are among the dead

(CNN) In what conservationists have called a "catastrophic event" for the rare animal, twenty-one greater one-horned rhinos, including 10 calves, have drowned in the monsoon-driven floods that have submerged swaths of a national park in northeastern India.

More than 70% of the species' population is found in the Kaziranga National Park in India's Assam state, according to the International Union for the Conservation of Nature (IUCN), which warned that "there could have a devastating impact on the status of the species."

The greater one-horned rhino is a vulnerable species, according to WWF.

The 10 baby rhinos were aged between two and six months. The rhino deaths are a blow to the species' population, which was teetering at around 3,300 in the last IUCN count in 2013.

The rhinos were among 310 animals that lost their lives in the deluge, divisional forest officer Suvasish Das of Kaziranga National Park said in a statement, adding that 106 animals had been saved in a desperate rescue operation by the local community.

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