The Dallas County Medical Examiner's office has identified the driver who was killed Saturday when his 18-wheeler crashed through a guardrail on Interstate 30 in Grand Prairie and plunged to the pavement of the President George Bush Turnpike below.

The victim was James Anthony Long, 59, of Clarksville, Tennessee. The cause of his death remains under investigation.

The North Texas Tollway Authority on Monday released a harrowing surveillance camera video that shows the big rig -- apparently traveling at close to highway speed -- plunging off the side of the overpass into the north and southbound lanes of Bush Turnpike at 4:03 p.m. Saturday.

The flying truck and trailer narrowly missed other motorists, some of whom are seen in the video slamming on the brakes to avoid hitting the fiery wreckage.

One car appeared to be almost directly underneath the truck as it was airborne.

Some drivers stopped, got out of their cars and ran to try and help, but there was little they could do.

It is still not clear why Long's truck left the highway.

Bush Turnpike was closed for hours at the I-30 itnersection while the debris was cleared and new barriers could be installed.

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