The killing of tigers for their body parts for their supposed medicinal properties is common in India, the BBC reported.
The poachers entered the zoo in the Arunachal Pradesh capital of Itanagar and tranquilized a 6-year-old female tiger while three security guards were at dinner, police said.
The tiger was cut into six pieces, but the poachers were unable to carry the parts away before the guards returned.
Poaching has caused a sharp decline in the population of tigers in India. A century ago, there were an estimated 100,000 of the animals. A 2011 census counted about 1,700 tigers in the wild.
Other animals at the Itanagar zoo have previously been the victims of poachers. In 2006, three tigers and a leopard were poisoned. One tiger died.