Senior forest department officials said the leopard entered the Oil India Ltd's residential zone at around 7 am this morning and attacked an old person and four others who came to save him.
Forest personnel from Doomdooma rushed to the spot and fired two capsules of tranquilisers at the animal.
A huge crowd gathered at the spot and the leopard, who was yet to fall asleep due to the tranquiliser, attacked and injured at least eight others, including an army captain.
At this security forces personnel posted in the area fired at the animal and killed it, they said.