Authorities say the dump truck was unloading dirt at a construction site Friday afternoon in the suburb of Bee Cave when it tipped over on the man, who was standing next to it.
The man's name was not immediately released by authorities.
SEE ALSO: Security guard saves driver from burning dump truck
"It's an extremely tragic event, and our hearts go out to the family of this individual. This time of year is a very joyful time, so tragic events are much harder," Officer Kristen Dark with the Travis County Sheriff's Office told KXAN-TV.
The truck's driver was pinned inside the vehicle and had to be rescued by first responders. He was taken to an area hospital with non-life threatening injuries.
Travis County Sheriff's Office says the back of the truck had been extending to unload the dirt when it somehow lost its balance and tipped over on its side.
The Texas Department of Public Safety is investigating the accident.
The Associated Press contributed to this report.