According to officials, a woman passenger named Panga Janya Andher aged between 50 and 55, a resident of Ghas Dhongri, Nalasopara, boarded the VR-CCG Local to sell vegetables.
She was travelling in the front luggage compartment adjacent to motorman cabin of suburban local no 90024 CCG -VR local.
Officials said that at 4 am, an unidentified outsider boarded the train at Nalasopara and stabbed her 3 times in her lower right abdomen.
On hearing her screams, the motorman named Jitesh Rathod and a homeguard travelling in ladies coach beside the luggage compartment rushed to the woman's rescue.
The train guard SB Patil applied brakes at km no 55/8-9 at 4/02 hours, but the unknown person jumped out of the train on the eastern side.
The injured lady was taken down at Vasai Road station by on-duty RPF personnel and railway cops.
She was taken to Ravi Hospital, Vasai(W), where she succumbed to her injuries, said officials.
According to officials, the body has been handed over to her son Raju Andher.
Investigations are in progress as senior cops have rushed to the spot.