Guwahati, Sep 18 (IANS): Poachers killed another one-horned rhino in Assam's Kaziranga National Park, taking the toll of rhinos that have been poached this year to 21, Kaziranga Divisional Forest Officer S.K Seal Sarma said Wednesday.

In the latest incident, forest officials recovered the carcass of a male rhino near the Burhapahar range. The rhino was killed Tuesday night, its horn was chopped off.

"The male rhino was gunned down between Khorali and Borbhug forest camps," the forest official said. The forest guards responded to gun shots heard around 8 p.m. and started an operation.

A senior forest official said there was a heavy exchange of fire between the poachers and the forest guards for nearly a hour and half. However, the poachers escaped with the horn.

"Today morning, we launched the operation again when the rhino carcass was recovered with its horn sawed away and empty cartridges of AK 47 and .303 rifles were scattered near it," the official said.

Two rhinos, including one rhino calf, were killed by poachers in the Burhapahar range of the park last month and the horns were taken.

Although the Assam government has been taking several measures to strengthen security of the national park by deploying the elite Assam Forest Protection Force (AFPF), giving rewards to the officials for preventing poaching and others since last year, the poaching of rhinos continues in Kaziranga and other protected areas of the state.