Senior Sergeant Anthony Bond, of Dunedin, said police were called at 7pm on Monday after receiving a report of a two-vehicle crash near Riccarton Rd East.
A 37-year-old man who had been driving his vehicle in the wrong lane crossed double yellow lines and crashed head on into another vehicle.
The man had to be cut from the overturned car by Fire and Emergency New Zealand (Fenz) crews from Mosgiel and Lookout Point.
"He had what was described as life-threatening injuries," Snr Sgt Bond said.
A serious crash analyst attended and the road was closed for several hours while the investigation took place.
Yesterday at 10am, police received a report of a crash in St Andrew St near the Dunedin Railway Station.
One vehicle was on its side, and four other vehicles were involved.
Fenz and Hato Hone St John also attended.
One person was left in a serious condition and was taken to Dunedin Hospital.
The vehicles were towed and one lane was blocked for some time while the road was cleared, the spokeswoman said.
Later in Mosgiel, two people were trapped in the cab of their truck after a crash caused live power lines to tangle over the vehicle.
A Fenz spokeswoman said crews from Lookout Point and Mosgiel were called to the crash in Gow St about 2.50pm yesterday.
The truck crashed into a power pole, bringing it down on the vehicle along with the power lines.
The power lines were smoking, the spokeswoman said.
Police also attended the incident and a spokeswoman said the pair in the truck both had minor injuries.
The power pole and lines were on the road which was partially blocked for some time, the spokeswoman said.
