The fire at the temple in Ribba in Kinnaur valley, about 200 km from Shimla, started late on Friday and caused losses of nearly Rs 125 million, they said.
Besides, 170 Buddhist scriptures written over centuries by monks on birch paper rolls, many murals of Lord Buddha, antique jewellery and other artefacts have been reduced to ashes.
Himalayan pinewood planks that were used to construct the temple only fanned the fire, the officials said.
Built in 980 AD, it is one of the few Buddhist temples in the valley. It is still unclear how the fire began.