(KCEN) -- One person is dead after a semi caught fire on I-35 just north of West.

At 6:20 Thursday morning, an avocado truck headed from the Laredo area to Grand Prairie hit a concrete barrier, ruptured the fuel tanks, and caught fire in the northbound lanes of I-35 at exit 355.

"It was totally involved" by the time Tom Marek and other Abbott firefighters got there. "The whole 18-wheeler was onfire."

"We couldn't even use the service road," Marek added. "Shut downcompletely for about 40 minutes."

Some of the diesel fuel ran through a drainage ditch under the road. By the time firefighters got there, about 15-foot flameswere shooting out.

They got the fire out after about 45 minutes.

That's when they found the driver, burned beyond recognition.

"Fortunately thisis the only death we had out here today," said Trooper D.L. Wilson with the Department of Public Safety, "which is very sad, but it could havebeen much worse."

Traffic was light since it was early, so no other cars were involved. Traffic backed up for about three miles right after it happened.

Witnesses say they saw the driver was weaving in and out of the lane and didn't see the truck brake before hitting the barrier.

"We don't know if it's fatigue or a medical condition" that caused the driver to weave, Wilson said. The "construction zone didn't cause this crash, but it's just a tight situationthrough here."

The truck was back upright by about 9:45 a.m., and the highway was reopened completely at 11:30 a.m.

Then the real cleanup began. Environmental crews had to dig up and take away all of the dirt on the side of the road because of the diesel spill.

The load of avocados was condemned by the health department.

There's no word yet on the identity of the driver, who was taken to the Dallas medical examiner's office.