Emergency services are at a single-vehicle crash on Shines Rd, Island Cliff, outside of Oamaru.
Police say that initial reports indicate there are serious injuries.
A Hato Hone St John Spokesperson said they were notified of the crash at 9am.
One ambulance is at the scene, and a helicopter is due to arrive.
The status of any patients is currently unknown.
A police spokesperson said three police units were at the crash and an update would be provided shortly.
Police are also advising motorists to avoid the Shines Rd area.
Fire and Emergency New Zealand shift manager Amanda Ensor said three appliances from Kurow, Duntroon, and Oamaru have attended.
Fire crews are assisting police.