The guards also recovered a 303 rifle, 10 bullets and an axe.
Assam's Principal Chief Conservator of Forests, Wildlife Bikash Brahma confirmed on Tuesday that the poachers had entered the park with the intention to kill one-horned rhinos.
"The incident took place around 1 am on Tuesday. The forest guards heard a gunshot and launched an operation immediately. The poachers fired at the guards when asked to surrender. Two poachers were killed in the ensuing gunfight," Brahma said.