"Keeping in view the sensitivity in the gang rape and murder case and to remove all doubts, if any, the government has decided to refer the matter to the CBI," an official statement quoted Chief Minister Virbhadra Singh as saying.
The Chief Minister took stock of the situation after returning to the capital from an official tour.
Accusing the police of shielding the "real culprits", residents of Theog town earlier on Friday blocked a national highway and gheraoed a police station to demand the probe by the Central Bureau of Investigation into the July 4 crime.
Even as protests were held in the state capital, shopkeepers shut shops in Theog and Kotkhai towns to express solidarity with the victim's family.
A woman hurled a shoe at one of the accused who was taken to a hospital here by police for medical examination.
The protesters blocked National Highway-5, which links Shimla with upper Shimla district, for several hours.
They also gheraoed the police station where Superintendent of Police D.W. Negi was present and broke windowpanes of his official car.
"We demand the case be handed over to the Central Bureau of Investigation. We want assurance from the Chief Minister (Virbhadra Singh)," an uncle of the victim earlier told reporters in Theog, around 35 km from here.
He said police remained silent on the gang rape-murder case for 10 days and all of a sudden announced the arrest of five more accused on Thursday.
"We have doubts the real accused are still roaming free," a protestor said.
In a related development, Inspector General of Police Zahur H. Zaidi, heading a Special Investigation Team formed to probe the case, went on leave on Friday.
Over a week after the crime, Director General of Police Somesh Goyal on Thursday said the police had arrested all six accused.
"One accused was arrested yesterday (Wednesday) and five others arrested today (Thursday) in the rape and murder of a girl in Kotkhai," he told reporters here.
The accused, aged between 19 and 42, included two Nepalese and two persons from Uttarakhand, mainly farm labourers settled in Kotkhai area where the crime happened.
The 16-year-old girl was offered a lift in a vehicle by the accused on July 4 when she was returning home from school. On the way, the accused raped and murdered her in a nearby forest. Her body was found two days later.
The arrested persons are prime accused Rajinder Singh, who offered her the lift, Ashish Chauhan, Subhash Bisht, Deepak Kumar, Surat Singh and Lokjan.
The police said the prime accused had developed familiarity with the victim, named Gudia or a child, as he offered her lift twice earlier.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)