The four went to the Sawarkar Nagar house of the woman (42), who is an RTO agent, on June 6 and demanded Rs 1 lakh from her to "hush up the matter", Thane Zone-V Deputy Commissioner of Police Balasaheb Patil said.
One of them even tried to videograph the woman's house, Patil said.
The woman later gave the accused Rs 10,000, but they kept pestering her to pay the full amount and threatened her with dire consequences if she failed to meet their demand, he said.
Police nabbed two of the accused - Shailesh Kadam (29) and Mohan Shinde (40) - on Tuesday and arrested one Shabad (who carried the camera to videograph the woman's premises) and Ganesh (journalist) yesterday.
They later seized the camera and Ganesh's ID card which mentioned that he was a journalist with a weekly newspaper, Patil said.
Offences have been registered against the four under sections 384 (extortion), 419 (cheating by personation), 452, 323, 506 (criminal intimidation), 34 and 84(k) of the Indian Penal code, police said.