Emergency services, including an air ambulance, were sent to the crash.
Sgt Kate Finlayson said: “Our thoughts are with the family and friends of the girl who died, and inquiries are ongoing to establish the full circumstances.
“I am appealing for anyone who witnessed the crash or the vehicles prior to contact us, external.
“I would also ask anyone who was in the area and who may have dashcam footage that could assist to please get in touch.”
The Scottish Ambulance Service said it sent several resources, including four ambulances, a critical care team and an air ambulance, to the scene.
A spokesperson said two patients were taken to Raigmore Hospital in Inverness.
The crash happened on a 13-mile stretch of A831 between Drumnadrochit, a village on the shores of Loch Ness, and Cannich, which is a village at the end of Strathglass.
The road passes through a sparsely populated area of farms, forests and lochs.