Officers have shut part of the A859, between Ardhasaig and Huisinish Junction, on the Isle of Harris.
It appears the crash happened at about 9.30am on Thursday morning and emergency services are currently on the scene.
No injures have been reported so far.
A police spokesman said: “The road is expected to remain closed for a significant period. There are no diversions. Your patience at this time is appreciated.”
More as we have it.