The truck was headed south on Interstate 45 when it suddenly left the roadway, Harris County deputies said.
The driver crashed into the guardrail, a grassy area and a tree. Authorities said the impact sheared open the trailer portion of the 18-wheeler, spilling empty Bud Light beer cans.
At the time of the crash, authorities said the driver was not wearing a seatbelt and was ejected from the cab. He ended up on the freeway, and suffered apparent trauma to the body, broken bones and facial injuries, according to deputies.
A witness at the scene told authorities he heard a portion of the crash before the 18-wheeler went off the road.
It's unclear if that sound was a tire or malfunction.