The crash happened around 3 p.m. July 1 near the Highway 15-501 exit.
According to the report issued Thursday, truck driver Ronald Eugene Graybeal, 50, of Newport, Tennessee, was headed westbound when he came up on vehicles that had slowed in front of him.
Troopers say Graybeal's truck was travelling at the posted speed limit of 65-miles-per-hour, but he failed to slow down.
Graybeal hit the back of a pickup driven by 38-year-old John Paul Llanio of Kannapolis. Llanio was killed and his pickup became wrapped around the front of Graybeal's semi.
The truck then hit a Chevrolet driven by 64-year-old Barbara Boda Caldwell of Mebane and a Nissan driven by 45-year-old Gary Dwayne Smith of Burlington.
Both cars were knocked to the side.
Smith's Nissan burst into flames. Both he and Caldwell also died.
Graybeal is charged with one count of felony death by vehicle, two counts of misdemeanor death by vehicle, DWI, and possession of methadone, marijuana, and drug paraphernalia.