Emergency services are at the scene of a serious three-vehicle crash near State Highway 7 in Hurunui.
The police said the crash was reported about 12:10pm on Weka Pass Road, near State Highway 7.
The road was closed and motorists were being urged to avoid the area.
"Road users should expect significant delays or delay their travel until this has been cleared," a New Zealand Transport Agency spokesperson said.
A St John spokesman said crews attended the crash and at least one person has been treated with moderate injuries.