Poachers have killed a rhino in Assam’s Kaziranga National Park with an AK-47 assault rifle and taken the animal’s horn, striking after a gap of more than 13 months, forest department officials said on Sunday.

Discovery of eight empty shells of an AK-47 assault rifle at the spot where the rhino’s carcass was found have led forest officials to suspect the role of some local insurgent groups, who are in possession of such sophisticated arms.

This is the first instance of rhino poaching in Kaziranga this year. There was no instance of poaching the 430 sq km park since April 1, 2019, and it had recorded three poaching deaths last year.

“The carcass of the adult male rhino was found by our personnel on Saturday evening at the Agaratoli range of the park with its horn missing. It seems the poaching incident took place on Wednesday,” P Sivakumar, director of the national park, said.

All the five national parks, 18 wildlife sanctuaries and zoos in Assam have been closed for tourists since mid-March due to the nationwide lockdown to prevent the spread of Covid-19. But there have been instances of movement of poachers during this period.

“There was some information about the movement of eight persons allegedly belonging to some extremist group from Karbi Anglong in the Panbari area with three AK series rifles. Combing operations were carried out based on the information,” Sivakumar said.

“This is the first case of use of AK-47 rifles to kill rhino in the Agaratoli range of the park. Only trained groups who know how to handle such arms can indulge in such kind of poaching. We suspect they had come from the nearby Karbi Anglong district,” he added.

Last month, villagers on the eastern side of the park had caught a suspected rhino poacher with arms and handed him over to the police and forest officials.

“Kaziranga did its best to keep poachers away in last 13 months. Unfortunately it was the poachers’ day (sic),” Rohit Choudhury, a wildlife activist, tweeted.

With a population of around 2,400, Kaziranga is the largest habitat of the one-horned rhino in the world. It is also a hunting ground for poachers who target the animal for its horn—prized as medicine in China and some other Southeast Asian countries.