Calcutta, Nov. 5: Police were today handed over charge of investigating into the mafia’s role in railway’s tender allotments.

An extortion racket in the guise of a contractors’ organisation came to light after the Confederation of Indian Industries complained to police commissioner Prasun Mukherjee that an engineering firm that had bagged its contract was being issued threats.

Bhowanipur police arrested six gang members on Thursday when they stormed the office of the firm.

They have been taken to the Lalbazar central lock-up for interrogation. However, a hunt is on for the two masterminds.