State troopers said a wrong way driver caused a major accident that killed two people and backed up traffic on Interstate 35 for miles.

It was a horrific collision -- the two cars that smashed into each other Tuesday night were barely recognizable when rescue teams arrived.

"We will be back out here in a couple of days to do a follow up. We'll do a digital map of the entire scene and get additional photos during day-light hour," said State Trooper Michael Smith.

Investigators do know that Tuesday was 22-year-old Jonathan David Chatham’s birthday.

Chatham, who is from Cedar Park, was driving his Ford Contour south -- the wrong way down I-35N.

Tx DPS

Joaquin Avila

Tx DPS

Jonathan David Chatham

Near mile marker 271 he crashed into Joaquin Avila, 58, killing him on impact.

Avila was heading north in his Kia Optima -- which spun into a truck driven by Baldemar Perez, Jr.

Perez survived the crash.

Pat Waltman owns a truck repair business near the crash scene.

"We've been here since 1996, we bought the property, built the building, it is the first accident, I've heard of like that, here," said Waltman.

It was not known where Chatham got on to the interstate -- he could have made access at a northbound-off ramp about two miles up the road in Jarrell.

Another possibility -- the frontage roads in the area allow two-way traffic, and Chatham, who was heading south, could have veered across the median and onto the northbound lanes.

As investigators tried to determine the case, Waltman was worried the crash will prompt the Texas Department of Transportation to convert the frontage road that runs past his business into one way lanes.

"They'd have to go up the road, turn around, go way back two miles and then turn around and come back up,” said Waltman. “I’m sure we will lose a lot of business if they make it one way.”

Investigators were waiting for a toxicology report before making an official ruling. They did say that both Chatham and Avila were wearing seat belts.