A lot of people have asked how to do this mission, so I've created a quick video walkthrough of how to get 3 stars on Leave the Canyon Before Nightfall.

You should be able to do it faster if you use multi-kill skills.

http://youtu.be/ZCIEdyQ30UY

Sorry the quality is low. I have a 7 year old PC: video capture and the game both have very high CPU usage, so I had to lower the recording quality to avoid bad lag in game.