A 54-year-old man remains in a critical condition with rib fractures and bruising to his lung after a tourist bus slid on black ice and rolled in Southland yesterday.
An eight-year-old boy also remains in intensive care with an abdomen injury but his condition has stabilised since the bus, which was carrying 30 people, crashed on the Te Anau-Mossburn Highway about 9am.
Police said his mother was by his side and she was receiving victim support.
The other 22 people who were injured had all been discharged from hospital, except a 62-year-old woman who had a fractured wrist.
The passengers who were unhurt spent the night in Te Anau and were expected to return to Auckland today.
The bus was travelling at 40km/h to 50km/h behind another bus near Mossburn when it slid and spun 180 degrees before coming off the road backwards, rolling onto its side and hitting a power pole.
While the cause of the crash was yet to be determined, police said road conditions were treacherous at the time.
The 37-year-old driver was from China and had been living in Auckland for the last five years.
"He is an experienced bus driver and is assisting police with their enquiries.''
The New Zealand Transport Authority attributed a "light shower of rain'' about 8am to the rapid deterioration of road conditions in the area.
Southland area manager Peter Robinson said the roads were inspected at 6am and 7am and no obvious ice issues were evident on the section where the crash happened.
Southern Lakes Helicopter pilot Mark Deaker, who attended the crash, said the roads were like a skating rink.