Yes, it can happen this fast. Always be vigilant, always be aware of your surroundings and the weather conditions.
This is an amazing dashcam video taken January 6, 2016 on westbound California Highway SR 23 (Grimes Canyon) from Fillmore to Moorpark.
The driver unexpectedly drives up to a flash flood that's overtaking the highway. The water doesn't look deep, but at the speed it's moving, with the debris, 6 inches is more than enough to move a vehicle or take down a person trying to walk through it. The debris could puncture a tire, damage the engine or build up under the vehicle and trap the occupants in the flood. There would be no swimming out of this, it's more mud and debris than it is water.
Check out the video below....