The incident, which Traffic Scotland has described as "serious", was reported shortly after 16:00. Police have said a motorbike is involved.
The site of the crash is about one mile from Urquhart Castle. Witnesses have said paramedics and an air ambulance are in attendance.
A diversion via Spean Bridge has been put in place.
The A82 Fort William to Inverness road has been closed by a collision between Drumnadrochit and Invermoriston.