"Be very, very mindful around trains," said Metrolinx spokesperson Anne-Marie Aikins.
Aikins said that police tell her the victim was pulled onto the tracks when he became entangled with the back of a train. She said she understand the victim's backpack got snagged.
Toronto paramedics said the man was pronounced dead at the scene.
She said police are investigating the death and have surveillance video of the incident.
"There wasn't anything unusual that was can see," she said of the video.
Aikins said there were a number of people on the platform at the time who are speaking with police. She said the victim was a 31-year-old male commuter from Peel region.
Police are not revealing the victim's name as they notify next-of-kin.