Teresa Amelia Williams, 24, was charged with second-degree murder in the death of Evadne Williams-Scott, who was two years and nine months old.
On Tuesday afternoon just before 4 p.m., Peel Regional Police said officers responded to a call about a "hysterical woman" who was barefoot in the snow on the balcony of a home at 3480 Colonial Dr. in Mississauga, just west of Toronto.
Police found the woman barricaded inside her home. When they got inside, officers had to use a stun gun to subdue the woman.
Difficult for 'entire community'
Acting Insp. Randy Cowan said officers found the toddler inside suffering from "obvious signs of trauma."
"This is going to be definitely a difficult one for the entire community," he said.
Neighbour Veronica Molyin witnessed the woman's behaviour on her balcony Tuesday afternoon and knew something wasn't right.
"In this cold, she wasn't wearing no shoes, no jacket," she said, adding the woman was screaming and at one point went inside and tried to climb out of the window.
Molyin said she decided to call 911 after her son told her that the woman had a young daughter.
Cowan said Williams is not known to police, who have interviewed the father. She does not have any other children that police know of, he said.
Officers are going door to door in the area to seek relevant information, Cowan said.
The cause of death has not yet been determined, although an autopsy is scheduled for later on Wednesday.