Scenes of misery and allegations of blame for the accident were playing out as police weighed the question of whether to charge a Kowloon Motor Bus driver with dangerous driving.

Seventeen-year-old student Yip Kwan-wun was killed and 35 injured when the double-decker that Chan Kwok-fai was driving flipped over on a roundabout in Tseung Kwan O around midnight on Sunday.

Form Five student Yip, who like most of those hurt was on the upper deck, was taken to United Christian Hospital but was declared dead at 12.56am. Twenty of the injured remained in hospital last night, with six in critical condition.

Chan, 36, was arrested on suspicion of dangerous driving but released on bail of HK$5,000 after being held overnight. Police said he passed a breathalyzer test.

The Route 692 double-decker flipped on its side around 12.20am while taking a roundabout adjoining Po Shun Road and Tong Ming Street.

Some passengers alleged the bus was going at a fast speed as it arrived at the roundabout. It was "so fast I did not even realize it was flipping over," said one.

Another said the scene after the accident was chaotic, with passengers from the upper deck falling to the lower one.

Among the shocking experiences was that of Sze Wing-kwok, who reached his crying son to find the boy's head shattered and bared to the bone.

A KMB spokeswoman said Chan joined the company in 2006 and had driven on Route 692 for 18 months. He was on his first run of the night when he crashed. The bus had been in service for 12 years and was inspected a week earlier, she added.

Secretary for Transport and Housing Eva Cheng Yu-wah said there was nothing wrong with the design of the roundabout. "We can introduce additional safety measures," she added, "but this will depend on the investigation report."

On that, Transport Department traffic engineer Ambrose Cheong Siu- yau said there were sufficient road signs approaching the roundabout. "These usually ask drivers to slow down," he said, "and there is also a clear sign of 50 kilometers per hour."

Still, experts from his department were meeting police and district councillors today to discuss how road signage might be improved.

As for claims about the bus going fast, Polytechnic University mechanical engineer Lo Kok-keung said a bus could flip over at around 40 kilometers per hour.

KMB managing director Edmond Ho Tat-man, who visited some of the injured at Queen Elizabeth Hospital yesterday, said the company will pay HK$30,000 compensation to each of the injured.

Chief Executive Donald Tsang Yam-kuen said he was shocked and expressed his condolences to the dead girl's family, while Secretary for Labour and Welfare Matthew Cheung Kin-chung said social workers are counseling the bereaved family and the injured.