A 32-year-old woman was allegedly raped by four persons near a railway track in suburban Kurla, a police official said on Tuesday.
All the accused have been arrested, he said.
The incident took place near the Harbour Line rail track in Sable Nagar locality late Monday night when the woman, a resident of Worli area, was looking to go to Lokmanya Tilak Terminus in Kurla area to board a train to Katni in Madhya Pradesh, the official said.
Before the incident, she arrived at Kurla in a train from Byculla. On reaching the Kurla bridge, she asked a passerby for directions to Lokmanya Tilak Terminus and followed him on the Harbour Line route, the official said.
While walking, the woman mid-way went to relieve herself in the bushes and the passerby, who was walking ahead of her to show her the way, disappeared, he said.
At that time, two men, who were consuming drugs in the bushes, allegedly attacked the woman and raped her, he said.
Two other men, who were passing by on a two-wheeler, stopped at the spot and also allegedly raped the woman and had unnatural sex with her, the official said.
The accused also robbed the woman of Rs 3,000 and snatched her "mangalsutra" worth around Rs 25,000 before letting her go, he said.
After the brutalised victim walked some distance, she met a woman who helped her alert Nehru Nagar police.
One of the accused who was following the woman after the incident was identified by the woman (who helped the woman) as resident of the locality where she lived, he said.
Based on the inputs, the police swung into action and arrested all the four accused within hours of the crime, Nehru Nagar police station's senior inspector Vilas Shinde said.
The accused have been identified as Shrikant Bhogle, Sonu Tiwari, Nilesh Baraskar and Siddharth Wagh.
Three of the accused were caught from Kurla, while Wagh was caught from suburban Vikhroli, he said.
The accused have been booked under rape, unnatural sex, assault and other relevant provisions, the official said.
The woman, who is a widow and has two children, was taken for a medical examination, he added.