"Five to six poachers in a group entered the park but our guards launched an operation immediately, killing two of them," said a park official.
"Other poachers managed to escape. Two .303 rifles and some live ammunitions were also recovered from the spot," the official said.
The park, a Unesco World Heritage Site, has been witnessing a spate in poaching of one-horned rhinos since the past two years.
According to official statistics, a total of 18 one-horned rhinos have been killed in Assam since January this year, while forest guards have killed seven poachers in anti-poaching operations.