More than one hundred animals, including 10 one-horn rhinoceroses, have died due to massive flooding at the famed Kaziranga game reserve in northeastern India, prompting Britain’s Prince William and his wife, Kate Middleton, to express their concern in a letter to park authorities.

The royal couple visited the park in April 2016 to learn about conservation and anti-poaching efforts.

The International Federation of Red Cross and Red Crescent Societies has warned of a humanitarian crisis, saying that more than 500 flood-related deaths in South Asia have been reported in this year’s monsoon, and about 9.6 million people have been displaced.