The Denver Post reports the crash happened at 3:40 p.m. Sunday at Yampa Valley Regional Airport in Hayden, about 25 miles west of the ski resort town of Steamboat Springs.
Few details were released, including the victims' names and the type of plane involved.
Airport manager David Ruppel says investigators with the National Transportation Safety Board were en route to begin their investigation into the cause of the crash.
The four injured people were taken to a Steamboat Springs hospital. Information on the extent of their injuries wasn't immediately available.
