The accused has been detained, they said.
The girl was playing with other children outside her house in Malakheda area last evening when accused Vijay Kumar offered her toffee, police said.
He then took the girl to an isolated area and raped her, they added.
Her family members later found her lying in an unconscious state.
The girl was first admitted to a local hospital, but was later referred to a hospital in Jaipur. Her condition is stable, Investigating Officer Sukhbeer Singh said.
A medical examination will be conducted to confirm the incident and the exact age of the accused, he added.