Police sub-inspector V S Bhaskar of the Mumbra police station told PTI that all the four, including the two women all from Mira Road, went to the slum near the Mumbra bypass and threatened people that they would be arrested for possessing and dealing in narcotics.
Even as the four threatened slumdwellers with action, others called up the Mumbra police who arrived on the scene and nabbed two of the imposters, yesterday.
The police identified those arrested as Pratima Chowdhary (28) and Vasim Rehman (32).
The police has launched a manhunt for two others, Sohel Khan and Shabina, who fled the scene.
Those held have been charged under Section 170 read with Section 34 of the Indian Penal Code, the police said.