The owner of the bus company involved in the deadly crash in Te Anau believes the road is widely regarded as dangerous.
Two people died after the rental car they were in collided with a bus on the Te Anau-Milford Highway on Tuesday.
The car was overturned and crushed in the collision.
Photos of the scene showed the bus door wedged shut and passengers being helped out of a window.
Later photos show plumes of thick black smoke reaching high into the sky, with both the bus and car completely engulfed in flames.
The 16 people on the bus avoided any serious injuries.
Explorer Tourlines owner Stephen Cook says it's well known to be a dangerous stretch of road.
He believed the car crossed the centre line before the impact, but doesn't yet know why.