Three-year-old Elijah, who wandered outside on a bitterly cold morning in Toronto wearing only a T-shirt and a diaper, has died after being found between two houses on Thursday morning.

"We knew it was bitterly cold out there, it was a dangerous situation," Toronto Police Chief Bill Blair said Thursday afternoon.

"One could only imagine the depth of (the family's) grief... It's a tragedy for the entire community."

The boy was staying at his grandmother's apartment, located at 145 Neptune Dr., near Bathurst Street and Highway 401, when he went missing.

He was put to bed at 9:30 p.m. Wednesday night, and was discovered missing at 7:30 a.m.

After reviewing security camera footage, police said he left the apartment building, alone, at 4:05 a.m., and was seen on the driveway at 4:20 a.m.

He was seen wearing a T-shirt, diaper and boots, police said.

Elijah is seen in security camera footage released by Toronto police.

So far, there is no indication of where he may have been going or trying to go, Toronto Police Insp. Frank Barredo told media shortly before noon.

And neighbours told CTV News' John Vennavally-Rao that the apartment door would've locked behind him.

When Elijah left the building, it was -17 C in Toronto, but felt like -28 with the wind chill. When he was found, it was -19, and felt like -30.

A group of neighbours join in the search for Elijah.

Neighbours, friends, strangers and police from other divisions joined in an hours-long search for the boy.

"He is a sweet little boy," a family friend told media, describing him as shy and good-natured.

Elijah was found at approximately 10:15 a.m. by two volunteer searchers, near an air conditioning unit in the side yard of a home on Baycrest Avenue, approximately 300 metres from the apartment where he was staying.

The homeowner said she learned about the search for Elijah earlier in the day, and that her basement tenant didn’t hear anything from their side door.

“I saw in the news that everybody was looking in their backyard but I didn’t think I should go because I didn’t think he would be here,” Rachel Eizental said.

Police said they aren't sure of the route he took to get to the yard, nor do they know how long he was there.

Police were nearby, and called paramedics immediately.

Toronto police and EMS at the scene where 3-year-old Elijah was found.

A witness told CTV Toronto's John Musselman that police were crying as they carried the boy to the ambulance.

"It's terrifying to see a little boy like that," Pratheban Thurairagah said.

Flowers at the memorial site for 3-year-old Elijah.

Toronto paramedics told media that he was found without vital signs. He was transported to a nearby hospital in life-threatening condition.

At 2 p.m., Toronto police confirmed that the boy had succumbed to his injuries in hospital.

"We will do everything we can to support that family. We'll also connect them with our victim services," Blair said.

A police probe will investigate how Elijah managed to exit the apartment building without being detected.

With a report from CTV Toronto's John Musselman