State Highway 85 is closed this morning following a serious crash.

A police spokeswoman said they were called to the crash at Happy Valley Creek Bridge, about halfway between Waihemo and Green Valley, at about 8.10am. 

"Initial indications suggest there are serious injuries,” the spokeswoman said. 

The road is closed between Kyeburn and the Macraes Rd intersection at Waynes.

Emergency services are still at the scene and NZTA warned it could be hours before the route is reopened. 

Motorists are advised to expect delays or take an alternative route.