In most cases, the answer is yes.  First, Colorado law spells out when you need to call the police to report an accident.

Colorado Revised Statutes Title 42, Article 4, Part 16, in section 42-4-1606 says that in Colorado, a driver who is involved in a traffic accident must report the crash if it resulted in: injury to, serious bodily injury to, or death of any person, or any property damage.

So a car accident needs to be reported in Colorado (to the nearest office of the local police or sheriff's department) even if no one was hurt, as long as one or more vehicles incurred even a very minor amount of damage.   Occasionally, there are exceptions (like when the police department is on weather alert).  In those cases, you should still file a counter report with the police as soon as possible.