Investigators found marijuana and a marijuana pipe inside the car that Jon Jones allegedly abandoned moments after a hit and run crash in New Mexico ... cops say.
TMZ Sports has obtained the police report ... in which cops say witnesses saw a man believed to be the UFC champ run from the crash scene moments after slamming into a car carrying a pregnant woman.
One witness says Jones got out of his car -- a silver Buick -- and then went back into his car to grab a "large handful of cash" ... before running off on to a hill.
At one point, a witness say Jones jumped a fence in his escape.
Story developing ...