According to police here, the accused offer lifts in their car to the unsuspecting women, kill them and steal their cash and jewellary.
The serial killings took place from Oct 12 to Oct 14.
The arrested include Chandrakant Talwar (35), Greshmi Talwar (32), Syron Rodrigues (20) and a 16-year-old girl.
Chandrakant Talwar and Syron Rodrigues were arrested last Saturday, Oct 17 in a Mumbai suburb.
Deputy Inspector General of Police (DIG) RS Yadav said, "The minor girl was present in the car when they murdered their victims."
"They would take the body to a lonely place. In three cases, they burnt the body to avoid identification. In one case, they smashed the face with a heavy object," Yadav said.
"In all, they earned Rs 40,000 from the sale of the gold ornaments," he added.