A serious five-vehicle crash has closed a section of State Highway 1 between Hinds and Winslow near Ashburton this afternoon.

Multiple people are reportedly seriously injured.

Emergency services were alerted to the incident around 3:20pm.

The crash occurred between Windermere Road and Swamp Road, prompting a full closure of the highway.

A spokesperson for St John told Chris Lynch Media that one ambulance, a rapid response unit, and a manager are currently on scene, with additional resources en route.

Three rescue helicopters , one from Christchurch and two from Dunedin, have also been dispatched to the crash site.

Motorists are advised to avoid the area and expect significant delays while emergency services respond.

Further updates will be provided as more information becomes available.