A person died in a single-vehicle crash in Horowhenua district last night, police say.

The crash occurred on State Highway 1 north of Levin at 6.20pm, a police spokeswoman said.

The Serious Crash Unit attended the scene and SH1 between Kawiu and Paeroa roads was closed overnight.

"Motorists are asked to take alternative routes where possible, or delay travel," the spokeswoman said last night.