It happened due to non-application of skid-brakes on the wheels of the coaches by the staff deployed there. It was negligence on the part of the Railway employees.
7 Railway employees were suspended, which included 2 engine drivers, 3 carriage repairing staff and 2 operating department employees.
The engine was detached for change and the standard protocol of coaches being secured with wheel skid-brakes was not followed. Due to the gradient, the coaches rolled off.