Joint Commissioner of Police (Crime) Pallab Kanti Ghosh said that the apartment owner was the kingpin of the racket, while the other three were his friends and partners.
Two women were rescued from the apartment, he said.
The owner of the apartment also owns a medicine shop in the area, besides having partnership in an event management company, Ghosh added.
In another incident at Baisnabghata-Patuli police station area yesterday, a mother poisoned her son and later consumed poison herself to commit suicide in protest against her husband's affair with another woman, Ghosh said.
Even as the son died today, the mother was still fighting for life in city hospital, he said.
The third incident was reported from Jorasanko police station area where a complaint had been lodged by the family members of a fruit seller at Mechhua for his alleged abduction.
Earlier, the family filed a complaint of missing of the fruit seller Sohail Akhtar on January 1, Ghosh said.