The victim was playing with her friends outside her house at a transit camp in Dharavi slum on Tuesday night. But, when her mother came out of the house, she could not find her, Deputy Commissioner of Police D Kulkarni told PTI.
As she continued searching for her daughter, the victim was found crying near a public toilet, the officer added.
"The girl was bleeding. The victim's mother took her to Dharavi police station where an FIR was registered under IPC sections 363 (punishment for kidnapping) and 376 (punishment for rape)," the DCP said.
The victim is presently undergoing treatment at Sion hospital, police said adding that they were trying to identify the rapist and several people in the area have been questioned.