A mother has described how she saw her young son struck by a car before the vehicle was driven over the boy again so the driver could flee the scene.
Liam is in a critical condition in hospital
Nicola Watkins said three-year-old Liam Brickell was "thrown into the air" from the impact of the collision in Merseyside and the driver "just looked at me and drove off".
She had been holding Liam's hand on a pelican crossing in New Ferry, at about 1140 BST on Tuesday, when the maroon Vauxhall Cavalier hit him.
On Thursday Liam was in a critical but stable condition at Arrowe Park Hospital, Wirral, after the accident at the junction of Bebbington and New Chester roads.
Ms Watkins, 26, said: "Liam was holding my hand as we crossed the road. He knows his Green Cross Code and we waited for the green man.
"I just remember seeing the car and thinking he's not going to stop.
Whenever I close my eyes, I am back at the accident
Nicola Watkins, Liam's mother
"It hit Liam and threw him into the air. The man driving the car just looked at me and then drove off.
"I just started screaming 'somebody help my son'. Whenever I close my eyes, I am back at the accident. The last few days have been horrific."
The Cavalier, registration L238 EVR, was later found abandoned on Wilton Road. It had not been reported stolen.
Officers say a man and woman were seen running from the car and are appealing for witnesses.
Liam's father, Alan Brickell, said: "It was devastating. Whoever did this is a coward."
Detective Inspector Dave Grisenthwaite, of Wirral CID, said: "This is about as horrific a thing as can happen to two parents.
"The sort of trauma they have been through is hard to imagine."