A man has been arrested for allegedly locking up some people working on a railway project and seeking Rs 10 lakh from the contractor for their release, Thane police said on Sunday.

The contractor was allotted work of building a protection wall at Kalyan station and the accused, identified as Vijay Kadam, had taken Rs 5,000 as "protection money" after issuing threats, senior inspector Bashir Shaikh of Kolsewadi police station said.