“His face collided with the road while he was being dragged by the vehicle along the carriageway,” the officer said. “The left part of his face is seriously injured and probably disfigured.”

Police arrested the 61-year-old minibus driver on suspicion of dangerous driving, causing grievous bodily harm. As of Thursday evening, the driver was released on bail after being held for questioning, though he was not charged. He is required to report to police next month.

The seven-year-old boy, a Primary Two student at Salvation Army Tin Ka Ping School, was walking with his sister from their home in Mei Tin Estate. The children were usually accompanied to school by their mother, but on that day she had to stay at home to look after her newborn.

Once outside the estate, the boy ran off the sidewalk and across Heung Fan Liu Street, when the green-topped minibus came and, failing to brake in time, hit him.

“The boy was trapped under the minibus and his schoolbag was entangled with something under the vehicle. He was dragged for about 20 metres before it came to a stop,” the officer said.

“He was conscious while being freed by firefighters. But he fell into coma in hospital” and is now in critical condition, the officer said.

Another police officer noted there were no pedestrian-crossing facilities in the area, adding that police would look into the matter and co-ordinate with concerned government departments.

The minibus was towed to a government vehicle plant in Tuen Mun for inspection. The New Territories South traffic unit is investigating the case.

Police figures shows 115 people died in 113 traffic accidents last year, slightly down from 120 deaths in 116 traffic accidents in 2012.