KEY POINTS:
A hospital was forced to declare a "mass casualty status" - a term normally used in civil defence emergencies - after treating 60 patients who, in a three-hour period yesterday, had fallen on black ice.
Southland Hospital treated people with broken arms, legs, hips and fingers. The rate of admissions to the emergency department ran at five times the normal level.
Most of the injuries happened when people simply slipped over.
Black ice is dangerous because it is transparent and cannot be seen against the dark road underneath.
So many people were admitted that the hospital was forced to set up an alternative emergency department, using a day-surgery unit to treat patients with minor injuries.
About 10 people had elective surgery cancelled as surgical staff treated patients needing urgent operations.
"Normally we would see 100 patients over a 24-hour period in our emergency department and we saw 60 in the space of three hours," said Southland District Health Board spokeswoman Megan Smith.
"Over the years we've not seen, in such a short time, such a high number of specifically ice-related injuries.
"It was a combination of some motor vehicle accidents but predominantly it was people just walking out and getting caught out on the black ice on the roads, like falling over and breaking numerous bits and bobs on their body."
The hospital was lucky staff were not affected by the icy conditions and were able to get to work, she said.
"We're bracing ourselves for more black ice [today] and asking the public to keep off the ice, stay at home and keep safe."
* Black ice stopped all flights at Invercargill Airport until 10.30am yesterday.
