Terming the incident as shocking, he said a team would visit the area to probe the incident, which occurred at a secluded spot near the school run by a mission.
"Eight of the nine accused have been arrested, and the one remaining will be caught soon," Soren told reporters in the presence of Director General of Police Rajeev Kumar and Home Secretary N N Pandey.
"The government will take the responsibility for the minor girls' education and train them in self-defence," he said.
The DGP said the arrested people belong to Santhal Parganas.
The incident happened at Lobda village under Littipara police station on Sunday night.