Emergency services are at the scene of the crash, which happened on the Waimakariri Bridge on State Highway 1 about 7.15am on Tuesday.
The crash has blocked the northbound lane.
St John ambulance spokesman Gerard Campbell said one person sustained moderate injuries and has been transported to Christchurch Hospital and another person was treated for minor injures at the scene.
A Fire and Emergency New Zealand spokeswoman said two crews were at the scene and no one had to be cut from the vehicles.