A serious crash has blocked State Highway 1 near Dunsandel this evening, leaving multiple people injured.

Emergency services were called to the scene near the intersection with Selwyn Lake Road just before 8pm after three vehicles collided.

A police spokesperson said one person suffered serious injuries, two others were moderately injured, and another person received minor injuries.

St John responded with multiple ambulances to treat those involved.

The crash has blocked the highway and police said the road is expected to remain closed for some time.

Diversions are being put in place and motorists are being asked to follow the directions of emergency services staff at the scene.