The diesel locomotive was standing in yard line no. 5A (also an extra shunting line between Platform one and two) at Anand Vihar car shed, according to official sources.
The engine started rolling by itself for about 40 m and derailed near the east end of the station with three of its front wheels coming off the tracks.
Reportedly, the probable cause of rolling down is suspected to be the failure of hand brakes.
As protocol demands, any engine driver has to apply the handbrake when a loco is shut down and "parked".
The rail traffic has been smooth so far after the incident
Currently, the driver has been suspended and an inquiry has been ordered into the matter.(ANI)