The victim, who has not been named, was crossing the road with his family in Chorlton-cum-Hardy when the accident happened.
He was struck by a silver Mitsubishi Galant at about 1310 GMT on Sunday, leaving him with serious injuries from which he died later in hospital.
On Monday police confirmed two men had been arrested in connection with the incident.
'Total tragedy'
The boy was later taken to Wythenshawe Hospital, where he was confirmed dead.
Inspector Ian Hales said: "This is a total and utter tragedy and my heart goes out to the boys' family who witnessed the whole incident.
"I can only imagine what they must be going through."
The accident happened after the car had just turned on to Hardy Lane from Barlow Moor Road.
Forensic examination
The boy was crossing the road with his mother and two other family members when he was hit by the car.
After he was hit by the car it continued down Hardy Lane until it turned left onto Burrows Avenue.
The car was later found abandoned on Riverside Avenue at 1330 GMT and is undergoing forensic examination.
A 21-year-old man from Fallowfield and an 18-year-old man from Moss Side were arrested on Sunday afternoon.
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