Emergency responders were called to the scene at Dundas Street and Cawthra Road at about 7:40 p.m.  of Tuesday.
Mississauga Fire initially confirmed that a child was struck by a passing train.  The child, believed to be four, was pronounced dead at the scene just before 9pm
The Transportation Safety Board of Canada (TSB) confirmed that an investigation into the crash has since been launched.
A spokesman for Metrolinx, which operates GO Train service, said in a statement that about 300 passengers were on the train when the child was struck.
“Metrolinx is assisting in the investigation of this incident. This includes questions about the protection around rail lines. There are many aspects to rail safety and investigators will look at all factors. Safety is always our first priority.” , James Wattie said in an email to CTV News Toronto Wednesday afternoon.
READ MORE: Child dead after being hit by GO Train in Mississauga, Ont.
Speaking to CP24 at the scene, a witness who owns a nearby garage said he was working at the time of the incident when he heard the train’s horns, followed by the loud squeal of a railway brake.
“When I came out of my garage, I see the train stopped.  This has never happened before,” Muhammad Tayyab said.
“Three children were screaming and crying very loudly.  I was shocked.  I ran there… I see the body, there was a child on the side… They were hurt very badly.”
Witness Muhammad Tayyab speaks to CP24 on July 27, 2022.
Tayyab said he saw a woman running towards the children a short time later and described her as being in complete shock.
It is unclear how the child ended up in the path of the train at the time of the collision or exactly where he gained access to the tracks.
However, local residents who spoke to CP24 afterwards said the lack of barriers on the train tracks is a known issue and it is not unusual to see people crossing the tracks to get to the other side.
To that end, crews were seen erecting fencing Wednesday morning in an area near the tracks that appeared unobstructed.
Crews install fencing near a section of railroad tracks in Mississauga, Ont.  on July 27, 2022.
Previously, the only barrier restricting access to the tracks at that location was a “no trespassing” sign.
An unobstructed area near a number of train tracks in Mississauga, Ont.  appears on July 27, 2022. 
An investigation into the crash is ongoing and this morning Ontario Transportation Minister Caroline Mulroney offered her condolences to the victim’s family.
“I spoke with the CEO of Metrolinx who informed me that his team is assisting with the ongoing investigation,” Mulroney said in a tweet.
Deeply saddened by the news of an incident involving a GO train that resulted in the death of a child.  My sincere condolences to the victim’s family.

I spoke with the CEO of Metrolinx, who informed me that his team is assisting with the ongoing investigation. — Caroline Mulroney (@C_Mulroney) July 27, 2022
Although police did not release the age of the child involved in the crash, Mississauga Mayor Bonnie Crombie said in a tweet posted Tuesday night that she was “very devastated” to learn of the “death of a young four-year-old.” . “The loss of a child is nothing short of a tragedy and my heart goes out to their family and loved ones as they mourn this unspeakable and immeasurable loss,” Crombie wrote. Pamela Fuselli is the CEO of Parachute, a Canadian organization committed to injury prevention, and says there are over 73,000 kilometers of rail tracks across Canada, but not all of them are closed to the public. “Unfortunately not every space can be separated by fencing or barriers,” Fuselli said. “In places where there’s a large population, where there’s a large volume of potential crossings or people wanting to cross from one side to the other, that has to be taken into account.” He said understanding the movement of people is key to preventing these tragedies and that “passive” preventative measures such as fences and barriers can help inform the public about where to cross safely. With files from Joshua Freeman