Police, Fire and Emergency New Zealand and Hato Hone St John responded to the crash in Stedman Rd about 11am.
A Hato Hone St John spokeswoman said it sent two ambulance and a rapid response vehicle.
They treated and transported one patient to Dunedin Hospital in a serious condition.
A truck carrying hay bales was seen parked on the side of the road, with damage to the front right.
A door from the car had been removed so the driver could be got out.
The front of the car was crumpled and there were skid marks streaked across the road.
At the scene, Constable Amie Manning, of Dunedin, said a male was trapped in the vehicle but had since been freed.
While there was "significant" damage to the front of both vehicles, the cause of the crash was not thought to be due to excessive speed.
"It’s not a high-speed crash. It’s conceivable that it was within the speed limits," Const Manning said.
