Hong Kong police say 19 people have been killed after a double-decker bus crashed in a suburb of the southern Chinese city.
A police spokeswoman says 17 men and two women were killed in the accident, which local media reports say happened when the bus tipped over on Saturday evening.
The spokeswoman did not have any more details and did not give her name, as is customary under department rules, reports News.com.au.
Photos and videos published by local media, or posted by users on social media, showed the gold-coloured bus lying on its side while emergency workers treated injured passengers nearby.
It was not immediately known what caused the accident but passengers quoted by local media said the driver was driving fast before the crash.
"It was much faster than I normally felt in a bus," an injured passenger told the South China Morning Post's online edition.
"And then it was like the tyre slipped, and the bus turned. It was really chaotic in the bus. People fell on one another and got tossed from side to side," he said.
Passengers had complained to the driver who was reportedly 10 minutes late and he then kept speeding up before the bus crashed, the Apple Daily reported, quoting injured passengers at the scene.
"(The driver was) intentionally using the bus to throw a tantrum," another injured passenger told the Oriental Daily.
The driver of the bus has been arrested for causing death and grievous bodily harm by dangerous driving, according to police.
In an updated toll in the early hours of Sunday morning the city's Hospital Authority said 10 of the injured were in critical condition, while another 20 were seriously wounded, officials said.
Most of the dead and injured were on the upper deck of the bus, Chan Hing-yu of the fire department told reporters.
The driver was suspected of being over the speed limit as he went down a slope and lost control of the vehicle, senior traffic superintendent Lee Chi-wai told reporters.
He was not in need of any medical treatment after the crash and was be sober, he added.
City leader Carrie Lam, who visited survivors at the Prince of Wales Hospital, expressed "deep sorrow" and pledged there would be an independent investigation.
Hong Kong promotes its public transport system as one of the best infrastructures in the world but fatal accidents do occasionally happen.
According to the South China Morning Post this crash is the Asian financial centre's deadliest traffic accident where a bus toppled from a bridge in 2003 and killed 21 people.
In 2008, 18 people were killed in another bus crash.
Fourteen people were injured last April when a double-decker tram tipped over, with a 23-year-old driver later arrested for dangerous driving causing harm to others.