The running suspect aimed a gun at the cop which caused the shooting. In a similar manner to what happened in Atlanta (though of course that was a taser)
https://www.denverda.org/wp-content...d-Shooting-of-William-Debose-May-1-2020-B.pdf
https://www.denverda.org/wp-content...d-Shooting-of-William-Debose-May-1-2020-B.pdf