The alleged incident took place in the hospital on July 14, they said.
The girl suffered injuries during the alleged criminal assault and was admitted to the hospital.
An FIR in this connection was registered yesterday at Premnagar Police Station after the girl was discharged from hospital.
The hospital authorities tried to hush up the case, the girl's family alleged in their complaint to police.
SP Akash Kulhari said preliminary investigations showed the girl's family was threatened by the hospital authorities.