The transit agency said the station crew spotted a child on the tracks around 1:40 a.m.
The TTC said a westbound train that was already out of service and was leaving the station was approaching the child. They said the child was walking along the boards over the power line that has 600 volts running through it.
Crews immediately cut the power to the tracks and then brought the child onto the platform, the TTC said.
Toronto police were also notified of the missing child shortly after.
Paramedics said they assessed a “female pediatric patient” but she had no physical injuries.
Police said officers brought the mother to the station to be reunited with her daughter.
The girl’s grandmother – who Global News has agreed to identify only by her first name Vida – said the four-year-old has gone missing twice before.
“She moves so fast, she moves very fast, believe me,” she said.
The grandmother also said the girl’s parents have to take extra precautions to ensure their child is safe. She said they don’t sleep at night and are constantly checking on her.
They also have extra locks and video cameras on the front and back doors.
Vida said the family believes one of the girl’s aunts accidentally left one of the locks unlocked Wednesday night.
Although it was too dark to see anyone leaving in the footage, it is believed she got out through the back door, the grandmother said.
Vida said the girls’ parents are “shaken up” by the incident, but said the child is doing “okay.”
She said the family is “grateful” and “thankful” for everyone who was involved in rescuing her granddaughter.
“Safety is our top concern and on review of CCTV, we can’t determine how the child got to track level,” the TTC said.
“We’ve checked fencing in the area and it appears secure, but we are going back to do a more intensive inspection,” the transit agency continued. “This is a concerning, but thankfully, very rare, occurrence.”