The TTC is investigating an "incredibly ill-advised stunt" on the Scarborough Rapid Transit system.

A video posted to YouTube on July 1 shows two masked males carrying Canadian flags “surfing” on the roof of a moving subway train on Line 3. The two people then jump off as the train enters Kennedy Station and flee the scene.

The video, posted by ChaseTO, has the caption: “Celebrating the greatest country on earth by surfing trains in my home city. Happy Canada Day.”

The TTC posted about the incident on Twitter on Monday morning.

“These incidents are taken seriously and will be prosecuted to the full extent of the law,” wrote the transitagency.

“Dangerous and inconsiderate, to say the least.”

This morning, TTC spokesperson Stuart Green said they are now in the process of pulling video footage from "stations and trains." A description of the suspects and more details about what happened are not available at this time, he said.

"Goes without saying that stunts like this are incredibly dangerous and illegal. They can lead to serious injury or death as well as service delays and massive inconvenience for our customers,” he said in a statement.

Speaking with CP24 this afternoon, Green said this kind of behaviour is "really dumb, frankly."

"There are all sorts of reasons that people just should not be doing this sort of thing," he said, adding depending on the outcome of the investigation, there could be some "very serious consequences."

Green said those found to be responsible could get a $425 fine for disobeying TTC bylaws, but could also be charged criminally by police with mischief interfere with property.

Last August, the TTC investigated a similar “train surfing” incident after a three-minute video surfaced of a man hanging from the back of a moving underground subway train at Bathurst Station that was travelling westward. The man can be seen arriving at Spadina Station and running away.

TTC special constables investigated this incident, which they believe happened sometime around August 20, 2021.

The account where the video was posted, ChaseTO also features clips of people climbing to the top of Niagara Fallsview Casino and the former Kingston Penitentiary.

--with files from Chris Herhalt