FORT WORTH (CBSDFW.COM) – A deadly wreck snarled traffic on Fort Worth’s South Freeway Thursday morning.

It was just after 7:30 a.m. when traffic slowed on Interstate-35W. The unexpected change caused a driver to loose control and slam into a concrete wall, near East Morningside Drive.

There had been no major traffic event before the crash.

“Many of the vehicles slowed because of an unknown reason, maybe because traffic was heavy. You know how traffic picks up and slows down?” Fort Worth police officer Sharron Neal explained.

According to police, the car hit the wall, bounced back into traffic and was then hit by an oncoming 18-wheeler.

A 25-year-old white male was driving the car — a red-colored Pontiac.

“This individual was deceased on the scene when police arrived,” Neal said.

The driver of the semi was not injured.