Dinesh (29) and Thamarai (28) from Chennai were taking a stroll in the park when the bison suddenly appeared from behind a bush and attacked them, resulting in the couple loosing their footing and falling some 25 feet down, police said.
Other visitors in the partk raised an alarm and managed to drive away the animal.
The couple were administered first aid at the Government Hospital in Coonoor and later brought to the government hospital here as the woman's injuries were serious in nature, police said.