The driver of a flatbed truck is dead after the load of stone and construction material he was carrying crushed the cab of his truck during a crash on Highway 400 just north of Highway 88 Wednesday.

The crash happened at 11:30 a.m., when the flatbed driver came up behind a slow-moving dump truck travelling north in the right lane of the highway. The dump truck had its four-way flashers on, but for some reason the flatbed driver didn't notice the slower-moving vehicle until the last second.

The flatbed driver slammed on his brakes, but ran into the back of the dump truck. Both the braking and the impact caused the construction material to shift and slide forward, crushing the cab of the truck.

Another transport travelling behind both trucks swerved into the centre lane, but clipped the back corner of the flatbed as it partially jutted out into the centre lane. The second impact twisted the flatbed, pushing it into the ditch. It also ripped open the side of the cab and trailer of the third truck.

Bradford resident Randy Frampton was working in a nearby shop on a property that backs onto the highway when the crash occurred. He said he heard the noise of the impact, looked out the window and ran to the scene.

He could see one of the flatbed-truck driver's hands through the debris and wreckage and it wasn't moving, he said, so he knew the driver didn't make it.

"It looked like the whole compartment collapsed from the load of the brick," he said, referring to the landscaping stones the truck was carrying.

Debris from the flatbed and the load was spilled across all northbound lanes and one southbound lane. Other vehicles received minor damage as they hit the rocks and steel that littered the highway.

The driver of the flatbed, a 50-year-old Mississauga man, was pronounced dead at the scene.

Emergency personnel and firefighters from Bradford West Gwillimbury worked for more than three hours to remove the body, which was trapped in the cab under the debris.

The driver of the third truck received a cut to his arm. The driver of the dump truck wasn't injured.

"Why he didn't see the truck, I don't know," OPP media relations Const. Dave Woodford said of the flatbed driver at the scene of the crash.

An autopsy was conducted Thursday morning to try and determine if a medical condition could have caused the crash, Woodford said. Results were not available at press time.

The section of Highway 400 has gained recent notoriety for a growing number of crashes. It was along this same stretch that truck driver David Virgoe of Innisfil was killed last year when his rig was clipped by a street racer, and he swerved and rolled in the ditch trying to avoid hitting other motorists.

Frampton, who has worked in the shop alongside the stretch of highway for years, said he frequently sees and hears accidents.

"People drive fast and nobody pays attention," he said.

Woodford said there is no apparent design flaw in the highway along that stretch, and that most accidents can be attributed to driver error.

"It's because people don't pay attention to what they're doing," Woodford said.

He said traffic on Highway 400 has almost doubled in the past decade, and some longtime commuters haven't made the adjustment. They are driving as if there are the same number of cars and trucks on the road as there was 20 years ago, and it isn't safe, he said.

"You can't let your guard down."

Police have not released the name of the victim.