The Mumbai police made the first arrest on Sunday, in connection with Friday's alleged gang-rape of a woman in her slum, near Matunga railway compound wall.
Allegedly, the woman was gang-raped by seven men after a quarrel between one of the accused and the victim's husband.
The police said that they have arrested 20-year-old Ganesh Ingle, a Dharavi resident, who is an unskilled laborer.
"We feel that Ingle's interrogation might lead us to other six accused. He has been remanded to police custody for three days," an Matunga police station official said.
Two of the seven involved in the gang-rape and attack on her husband on Friday were known to the couple, the police said.
According to the victim's statement, two of the accused, Siddhu (20) and Anup (22), are known to the couple for the past three years. Siddhu had quarreled with the victim's husband on Friday evening.
At around 11.30 pm, seven persons allegedly barged into their shanty when they were asleep, dragged the victim's husband, assaulted him and gangraped her for two hours.
An FIR under Sections 323 (voluntarily causing hurt), 506 (criminal intimidation), 376 B (gang-rape), 377 (unnatural sex), 120 B (criminal conspiracy) and 34 (common intention) of the Indian Penal Code (IPC) was registered against the accused after the couple lodged a police complaint on Saturday morning.