"Stringent action will be taken against the culprits," Mr Chavan told reporters. Five men have been arrested for the crime.
The woman was raped last Thursday at the Shakti Mills, an abandoned textile mill in the city, while on assignment with a male companion. She was taking pictures of an abandoned factory for a Mumbai magazine. It is not clear whether her companion is also a journalist.
Shakti Mills is widely known to be used as a shelter by drug addicts.
The five men raped her in turns after assaulting her companion and tying him up with a belt. Police are still trying to trace a cellphone with which the men took photographs of the victim after the rape.
Mumbai has long been considered one of the safest places in India for women to travel alone, even at night.
On Sunday, about 1,000 people gathered in south Mumbai to stage a silent protest. Some wore black armbands, while others carried placards reading 'Stop rape' and 'City of shame'. Other protests were held in Tamil Nadu, Calcutta and Assam.
In December 2012, a gang rape in New Delhi sparked similar protests. In response, the government passed legislation increasing prison terms for rape and making voyeurism, stalking, acid attacks and the trafficking of women punishable under criminal law.
The trials of the four men and one juvenile accused of the New Delhi attack are expected to conclude within the next three weeks. The verdict on the juvenile suspect is set for August 31. Closing arguments in the trial of the four adult suspects started on Thursday.
To read a popular blog article by an American student about sexual violence in India, click here.
Photo: one of the suspects in the Mumbai gang rape taken into custody. Credit: (C) AFP