Those detained were residents of Kotkhai and nearby areas, sources in the police department said, without giving further details.
Meanwhile, various social organisations continued to stage protest and a youth group took out a candlelight march from Sanjauli to The Ridge today.
Pawan Khimta, who led the march, said that such a crime had never been heard of before in 'Dev Bhoomi' Himachal Pradesh and demanded justice for the victim.
He demanded that the matter be heard in a fast-track court.
The Class X girl was raped and murdered on July 4 and her body was recovered from a nearby forest two days later.
BJP's chief spokesperson Rajiv Bindal said the law and order situation had deteriorated in the state and the Kotkhai incident was a glaring example. The governor should intervene and President's Rule should be imposed in the state, he added.