Jayme Erickson, the paramedic, spent more than 20 minutes trying to save the life of her 17-year-old daughter Montana, who she did not initially recognise due to the severity of the injuries she had sustained.
The teenager ultimately died a few days later in the hospital.
The crash occurred on 15 November. Ms Erickson said her "worst nightmare as a paramedic has come true" in a message she posted to her Facebook.
According to The Washington Post, the incident occurred in Airdrie, Alberta, where Ms Erickson was on duty. She and a colleague were called out to the scene of a serious car crash. When they arrived they found a pair of teenagers who had been out walking their dog and who were injured after their car collided with a truck.
The passenger in the car had been critically injured and was pinned inside the vehicle. Firefighters were called to help extract the passenger. During that time, Ms Erickson stayed inside the vehicle with the passenger, ensuring the girl’s airway was clear.
The teenager was eventually airlifted to a nearby hospital, after which Ms Erickson went home to end her shift. Shortly after returning home she was visited by police officers who told her that Montana had been in an accident and had been rushed to an emergency room.
When Ms Erickson arrived at the hospital to see her daughter, she found the girl from the original accident who she had sat with for more than 20 minutes.
"On entering the room, to her horror, she found the girl who she had sat with in the back of the crumbled vehicle, keeping alive … was Jayme’s own daughter. Jayme unknowingly was keeping her own daughter alive," Richard Reed, a fellow paramedic, told reporters during a Tuesday press conference.
Montana eventually died in hospital three days after the crash. Both the driver of the car and the passenger of the truck survived, according to local reports.
An investigation into the crash is ongoing.
Ms Erickson shared her grief in a Facebook post after her daughter died.
"The pain I am feeling is like no pain I have ever felt, it is indescribable," she wrote. "The critically injured patient I had just attended to was my own flesh and blood. My only child. My mini-me."
She wondered openly about who her daughter might have become, had she survived the accident. Ms Erickson said she was grateful for the 17 years she had with her daughter.