The 19-year-old accused allegedly kidnapped the child from a housing complex in the Vashi area on Thursday and was caught by residents, an official said.
He said the girl was playing near her house in the complex around 8 pm when the accused took her away and allegedly molested her.
Alert residents caught him and handed him over to the police, he said.
The official said a case has been registered under section 137(2) (kidnapping) of the Bharatiya Nyaya Sanhita and Protection of Children from Sexual Offences (POCSO) Act, and further probe is underway. PTI COR ARU