Emergency services are responding to a bus crash south of Timaru, which has blocked the northbound lane of State Highway 1.
The incident happened between Timaru and Pareora.
It appears a commercial bus left the road and crashed into a ditch, police said.
Police were alerted about 4.30pm, however there are no reports of injuries.
Southbound lanes remain open, however motorists should expect delays while emergency services work at the scene.