GWINNETT COUNTY, Ga. -- Authorities say a jackknifed tractor-trailer is responsible for blocking traffic for hours on a major Gwinnett County thoroughfare, Tuesday.

According to the Georgia Department of Transportation, the accident happened before 3 p.m. in the area of I-85 southbound near I-985. The resulting cleanup blocked all southbound lanes of the road and the full road wasn't reopened until around 4:40 p.m.

The exact cause of the crash is still under investigation but, according to Georgia State Patrol spokesperson Tracey Watson, the truck apparently hit a guardrail near a construction area during the crash.