The girl was abducted around 3.00 am from L J Road in Mahim when she was asleep along with her family members in their roadside shanty, a police official said.
Her father, a labourer, noticed that she was missing when he woke up and lodged a police complaint.
The girl was found dead in a deserted place on the same road around 10.00 am, the police official said.
Autopsy at the state-run J J Hospital revealed that she had been raped.
“We have registered an offence of rape with murder and also added sections of the Protection of Children from Sexual Offences Act,” said Vikram Deshmane, Deputy Commissioner of Police (Zone -V).
Police have formed multiple teams to investigate the crime, he said.