Unidentified miscreants set on fire the annexure building of an Upper Primary School in Arunachal Pradesh's West Siang district, police said on Monday.

The annexure building of the school at Lipu Bagra village, in which nursery, Class I, and Class II classes were held, was completely gutted in the blaze, the police said.

The Arunachal Pradesh school fire incident occurred on Sunday near Aalo, the district headquarters town.