The surveillance video, shot from the front of a GO train, shows one person standing on adjacent tracks while two others run in front of the train.
One of the runners crosses directly in front of the train before throwing themselves against a railing, narrowly dodging being hit.
The other runner veers off onto the adjacent tracks as the train passes by.
Metrolinx said the incident happened on May 20. The Crown agency said the video is of the Humber River overpass in Etobicoke, south of Highway 401 at Weston Road.
No one was injured in the incident, but Metrolinx noted that 100 Canadians are seriously injured or killed every year as the result of railway crossing or trespassing incidents.
Metrolinx said it hopes someone recognizes the youths and encouraged their parents to reach out to the transportation agency.
“If you recognize these young people, please get in touch with us,” said Steve Weir, Metrolinx manager of customer protective services. “We aren’t looking to be punitive, but we are very eager to speak with your children to help educate them and ensure they never ever take this kind of risk again.”