According to the police report obtained by TMZ Sports, the Florida Highway Patrol responded the wreck at 1:18 AM on a Miami highway. 

When they arrived, officers noticed Norton's 2017 F-250 pickup truck flipped on its roof. 

Norton and his female passenger suffered major injuries in the crash and were both transported to a nearby hospital. 

Now, cops are spelling out what caused the crash -- and all signs point to Norton making a dangerous decision behind the wheel. 

Cops say Norton was exiting the highway on the Northbound exit ramp when he made a last-second decision to switch to the Southbound exit ramp. 

As Norton (Vehicle 1) was making his move, he sideswiped another car -- a 2015 Maserati Quattroporte -- which sent Norton careening into a barrier and ultimately causing his car to flip. 

The Maserati came to a controlled stop -- and it doesn't appear anyone in that car was seriously injured. 

Cops determined Norton made an improper lane change -- and he was issued a citation. 

Guessing it's the last issue on his mind though -- as we previously reported, the 22-year-old lost his arm in the wreck and suffered other serious injuries. 

Also noted on the police report ... officials say Norton caused $15,000 worth of damage to the concrete barrier. Unclear if he'll be charged for the repairs, but it appears likely.