Outlawz Rapper Hussein Fatal -- Dies In Car Crash ... Rapped with 2Pac on 'Hit 'Em Up'

Hussein Fatal, one of the members of rap group The Outlawz -- a group founded by Tupac -- died in a car accident this weekend ... the group confirms.

Details surrounding Fatal's death are unclear at this point -- but the group posted a message on social media saying, "Rest in Paradise our brother Hussein Fatal. He passed away in a car accident. Pray for his family & kids at this time!"

Fatal performed on a bunch of songs with Tupac -- but most famously rapped the second verse on "Hit 'Em Up" ... the one that starts, "Get out the way, yo, get out the way, yo. Biggie Smalls just got dropped."

Fellow Outlawz member Napoleon went to Facebook to remember his friend ... writing, "He was my old group member and friend for over 20 years and he will be missed."

R.I.P.