Peel Regional Police Const. Thomas Ruttan says the call came in around 10 p.m. Police found two victims in a house at 179 Kingknoll Drive, in the area of Steeles Avenue West and Mavis Road.
"Both those victims were transported to a local hospital," said Ruttan. "The female has succumbed to her injuries. The male has life-threatening injuries and remains in hospital."
Police are asking anyone with information about the crime to call police.
"We're talking about a time of night when likely there were people walking up and down the street, even though it is cold," said Ruttan. "We are asking anyone who may have seen anything out of the ordinary, a vehicle, a person that may not belong in the neighbourhood. We want those people to come forward."