That person has been identified as 60-year-old Andrew Johnstone, of Durham. He was pronounced dead at the scene.
The large truck pulling a trailer landed on the edge of White Oak Creek - partially in the water.
The North Carolina Highway Patrol said the truck was headed north around 7 a.m. when it ran into the median and hit a bridge railing - bursting into flames.
The vehicle then ran down a steep rock embankment where it finally came to rest in the shallow water of the creek.
Eyewitness Demo Stavrou said the truck was behind him when it happened.
"All of a sudden, I don't know what happened, they said he passed out, after the fact, he lost control of his vehicle drove into the median and actually hit the overpass on the southbound lanes," said Stravrou. "I'm still shaken up about it I can tell you."
Stavrou said he called 911 and rushed down the embankment to help. First responders were there in just 10 minutes.
Troy Bullard said he also went down to help and the conditions - with the truck laying in the water - made it hard for firefighters to get to the victims.
"I have a new respect for those guys having to get into that water with those uniforms they have to wear," he said. "I don't know if you've walked in muddy nasty water, but your feet were just sticking as you were walking."
"They did an awesome job. I was amazed at how fast they were able to assess the situation and then come through for the people they were able to save," Bullard continued.
Troopers said there were five people in the truck. Firefighters from Morrisville, Cary, and Apex used ladder trucks to get down to the victims. They were lifted to the road above and rushed to the hospital where there was no immediate word on their conditions.
Troopers said Johnstone was seated behind the driver, 22-year-old Gerardo Daniel Pacheco, who survived. He's facing charges including misdemeanor death by motor vehicle along with failure to maintain lane control.
The crash caused major traffic delays during the morning rush hour. All but one of the NC-540 southbound lanes were blocked and one northbound lane was also closed.
The truck belongs to Greenscape Incorporated based out of Holly Springs.