A 66-year-old woman with dementia who wandered outside in bone-chilling temperatures has died hours after her calls on an east-end Toronto street were ignored, police say.

The woman was rushed to Scarborough Grace Hospital after she was found without vital signs in the Brimley Road and McNicoll Avenue area at around 6:20 a.m. ET, Toronto police said. Medical crews tried unsuccessfully to revive her and she was pronounced dead in hospital at around 7 a.m.

Police patrolling the area were alerted about the woman, who was found near a car in the driveway of a home lying face up by a woman delivering newspapers.

Her collapse was "probably" brought on by hypothermia, said Toronto police Sgt. David Dube. Her coat was found lying nearby.

"We don't suspect foul play at this time," he said.

The woman, who has yet to be identified, was reported missing by her family at about 4:45 a.m. in the Midland Avenue and Finch Avenue East area.

Neighbours heard the woman crying out in distress at around 2 a.m. but no one called 911 or came to her aid, Dube said.

The veteran officer, who's been on the force for 24 years, said he was "somewhat surprised" no one called police, noting it is a good community. He urged people to call police immediately if they hear someone screaming for help.

"If you're going to be a community member, I think we have an obligation to look after one another and do the right thing," said Dube.

The woman wandered away from her home as temperatures dipped to around –20 C, police said.

Police said finger marks could be seen on a vehicle in the driveway where the woman had likely tried to pull herself up off of the ground.

The City of Toronto declared an extreme cold alert Sunday, triggering a number of additional support services to help the homeless and other vulnerable people find shelter. The alert was called off Monday morning as temperatures started rising.