Southern motorists are being urged to take extra care owing to black ice on roads this morning.
Road conditions are thought to be a factor in a crash on State Highway 8 at Fruitlands near Alexandra about 8am on Thursday.
St John said one person was taken to Dunstan Hospital with moderate injuries following the crash.
Police are advising motorists to take care, and the NZ Transport Agency has issued a black ice warning for the Central Otago region.
Temperatures in the district are low - at 10am it was -3degC in Alexandra, -2 in Wanaka and 0degC in Queenstown
Meanwhile, Dunedin police have sounded the alarm about black ice and say sun-strike continues to cause crashes in the city.
Meanwhile, a senior officer has warned that anyone who failed to clear ice from their windscreen was in line for a fine - and scraping off a dinner plate-sized hole to peer through was not doing enough.
Senior Sergeant Craig Dinnissen, of Dunedin, said a few cars travelling into Dunedin had recently lost control coming south into the city.
''We've had a few cars losing their tails coming over from Waitati on State Highway 1 in the early morning. Some of those shaded areas aren't getting any sun.''
Even though there might be no frost showing in the morning, black ice could still linger, Snr Sgt Dinnissen said.
A number of crashes caused by sun-strike had been reported to Dunedin police recently, especially at intersections.
Snr Sgt Dinnissen said if a motorist encountered sun-strike, they should ''pull over and stop for a wee while'', as advised in the road code.
Last year, motorists had been fined for failing to properly clear their windscreens, and that could be repeated this year, he said.
The best way to clear ice from a windscreen was with a scraper or luke-warm water. Boiling water risked cracking the window because of the rapid temperature change, he said.
