A tunnel near Christchurch was closed last night after a truck blew its turbo engine, causing the tunnel to fill up with thick black smoke.
A St John Ambulance spokeswoman said emergency services were called to the Lyttelton Road Tunnel on State Highway 75 about 9.30pm last night.
She said a truck had blown its turbo engine in the tunnel filling it with thick smoke.
The tunnel was closed as a result of the smoke and re-opened about 10pm, she said.
One person was treated at the scene for smoke inhalation, and they were later taken to hospital by ambulance, she said.