A second child has died after a single vehicle crash in Vaughan on Sunday.
York Regional Police said on Monday night that a girl, 10, has died. Police announced earlier on Monday that a boy, 4, died.
Charges against the 16-year-old driver of the vehicle will be upgraded, police added.
Police said they were called to Athabasca Drive, near Dufferin Street and Teston Road, around noon.
The driver of a black, 2017 Mercedes C Class had gone off the road and hit three people in a residential driveway, police say.
A 10-year-old girl and a four-year-old boy were rushed to hospital with life-threatening injuries. Police said both died in hospital.
A male neighbour was also taken to hospital with minor injuries.
Const. Laura Nicolle of York Regional Police told reporters at the scene Sunday that before the crash, the children had been outside playing with their bikes when the neighbour noticed they were having an issue with a bike chain and came over to help.
"They were on their own property and that's when the vehicle went off the road and collided with them," Nicolle said.
"It's such a devastating situation."
A 16-year-old male from Richmond Hill was arrested at the scene. Police announced Monday that he is now facing multiple charges, including two counts of dangerous operation causing death and two counts of criminal negligence causing death.