An altercation that broke out in the backseat of a car led to one man's death along SH 45 early Tuesday morning, authorities said.

The Williamson County Sheriff’s Office said deputies were dispatched to a reported crash along eastbound SH 45 near County Road 172 around 12:15 a.m. July 4. According to a preliminary investigation, an altercation between two of six people occurred in a pickup pulling a boat. The driver of the vehicle pulled over and a man and a woman exited the truck to continue arguing.

As the altercation continued, the sheriff’s office said the driver got back into the truck and began to drive away, not realizing that the truck's doors were open. The sheriff’s office said both people “were knocked down (by the open doors) and as the vehicle drove off the tires of the truck and boat ran over both victims.” The sheriff's office has classified the incident as an accident.

The man, who has not been identified as of 1:30 p.m. Tuesday, died at the scene. The second victim, identified as the driver’s sister, was taken to St. David’s Hospital in Round Rock with serious injuries. In a press conference Tuesday, authorities said she is in the ICU with internal injuries and several broken bones. The driver was identified by the sheriff's office as Joe Harvey while his sister was identified as Heather Harvey.

Eastbound SH 45 reopened around 3:45 a.m. Tuesday, the sheriff’s office added.