The rhino and her calf were gunned down near Tunekati Forest Camp under Burapahar Range of the park yesterday, Kaziranga National Park Divisional Forest Officer, Ruhini Ballab Saikia told news agency Press Trust of India.
According to Mr Saikia, the security personnel launched a search operation after hearing gunshots around 11.30 pm. They found the bullet-riddled carcasses of the rhinos lying near each other in the morning.
The official further said several empty cartridges of AK-47 assault rifle were also recovered from the spot.
With yesterday's deaths, the toll of rhinos killed in Kaziranga this year rises to five. Poachers had slaughtered two rhinos earlier this year. While one was killed at Hatibali Chapori in the national park's sixth addition area in February, the other was killed at Burapahar Range of the park in April, a forest official said.
18 rhinos were poached at the national park last year.