The incident occurred at around 4 PM yesterday when the boy was crossing the track to get onto the platform while a local train was approaching the station, an RPF official said today.
When the commuters standing on the platform raised an alarm, the constable standing there leaned forward and pulled the boy up.
The CCTV footage shows the train was closing in at the station when the boy had just been pulled up.
The identity of the constable is not yet known.