Two people were killed in a Tesla crash in Texas over the weekend, with local authorities saying that no one was driving the vehicle at the time of the incident.

The crash, according to a regional KHOU 11 report, occurred around 11:25 p.m. local time on Saturday in the Carlton Woods subdivision on Hammock Dunes Place. The car, identified as a 2019 Tesla Model S, was traveling “at a high rate of speed” when it encountered a slight curve and went off the roadway. The car ultimately struck a tree and erupted in flames.

Speaking with reporters, Harris County Precinct 4 Constable Mark Herman said investigators are “100 percent certain” that no one was in the driver’s seat at the time of the crash.

“They are positive,” Herman, who noted the fire took nearly four hours to extinguish, said. “And again, the height from the back seat to the front seat, that would be almost impossible, but again our investigators are trained. They handle collisions. Several of our folks are reconstructionists, but they feel very confident just with the positioning of the bodies after the impact that there was no one driving that vehicle.”

At the time of this writing, only the ages of the victims—59 years old and 69 years old, respectively—had been reported. One person was discovered in the front passenger seat of the vehicle, while the other was in the backseat.

Reached by Complex for additional comment on Monday, Chief Investigator Mitchell Weston of the Harris County Fire Marshal’s Office offered the following:

“Lithium-ion batteries are generally safe with the control measures engineered to prevent failure. However, high speed impacts such as those that can occur in automobile accidents can result in a failure that leads to thermal runaway. Thermal runaway can occur when the partition that separates the chemical components of the battery is damaged, causing uncontrolled contact of the separated materials in the battery.”

Complex has also reached out to Tesla for additional comment. This post will be updated accordingly.

On Saturday afternoon, Musk shared a tweet stating that Tesla vehicles with the Autopilot feature engaged are now approaching the milestone of having a 10 times lower chance of an accident when compared with the average vehicle. The tweet included a link to Tesla’s first safety report of 2021, which showed that—in the first quarter of the new year—the company had registered one accident for every 4.19 million miles driven in which drivers were using Autopilot.