Indian officials are investigating the brutal killings of rare rhinos at a flooded national park in eastern India.

Authorities say poachers have shot and dehorned four rhinos in the past two days, killing three of them, at the Kaziranga National Park in Assam state.

In one attack Wednesday, poachers shot the rhino, then cut off its horn, nose and part of its ear. Veterinarians worked to save the wounded animal, but said the chances of its survival are slim.

The 430-square-kilometer Kaziranga is home to the majority of the more than 3,000 one-horned rhinos in the world.

Officials say floodwaters in Assam have forced the animals to seek higher ground, making them more difficult to protect from poachers. The rhino's horn is sold in Asia, where it is coveted for its reported medicinal and aphrosdisiac qualities.

Indian Environment and Forests Minister Jayanthi Natarajan ordered the investigation into the attacks to be completed within a week.

Natarajan said, “I am shocked and distressed by the callous exploitation by unscrupulous poachers of the natural disaster of floods and of helpless animals fleeing to find shelter.” She added, “I am determined to ensure that these criminals are brought to justice and that such incidents do not recur in the future.”

Animal rights groups and local residents Thursday protested what they say is the government's failure to protect the rare rhinos.

Floods this week have killed at least 18 people and displaced nearly two-million others in Assam.

In July, floods triggered by monsoon rains killed at least 80 people and displaced thousands of others. More than 600 animals drowned after most of Kaziranga was submerged.