The guy driving the Walmart truck that crashed into Tracy Morgan's limo bus Saturday morning has been charged with death by auto ... TMZ has learned.
The Middlesex County Prosecutors Office says 35-year old Kevin Roper was charged with 1 count of death by auto and 4 counts of assault by auto.
Roper's bail has been set at $50k ... and prosecutors expect him to surrender.
As we previously reported, Morgan was riding in a limo bus on the NJ Turnpike on his way home from a gig last night ... when it was rear-ended by an 18-wheeler and overturned.
Tracy and another passenger were airlifted to a nearby hospital where they remain in critical condition. Another passenger, James McNair, was pronounced dead at the scene.
According to reports ... Morgan's opening act Ardie Fuqua -- who posted a photo of Tracy roughly 30 minutes before the accident -- is also in critical condition.
Prosecutors say the cause of the 6-vehicle wreck is still under investigation.