TWO men died after a Tesla vehicle that U.S. authorities believe was operating without anyone in the driver’s seat crashed into a tree Saturday night north of Houston.

One of the men was in the front passenger’s seat and the other was in the back seat of the Tesla, which was traveling at high speed along a curve before it hit a tree around 11:25 p.m. local time, Harris County Precinct 4 Constable Mark Herman said in an interview Sunday.

“Our preliminary investigation is determining — but it’s not complete yet — that there was no one at the wheel of that vehicle,” the constable said. “We’re almost 99.9 percent sure.”

It took emergency responders about four hours and roughly 32,000 gallons of water to put out the fire that engulfed the electric vehicle, Constable Herman said. High-voltage batteries like the ones used in Teslas can reignite after being damaged, even after firefighters have extinguished a fire, according to the U.S. National Transportation Safety Board.

As of Sunday, authorities still were probing whether the front passenger airbag deployed and whether the vehicle’s advanced driver-assistance system was enabled at the time of the crash.

Neither Tesla Inc. nor the National Highway Traffic Safety Administration, the top U.S. auto safety regulator, responded to requests for comment.

Tesla tells drivers using its advanced driver-assistance system, known as Autopilot, to pay attention to the road and be prepared to take control of the vehicle. It also says that driving with the Autopilot system engaged is safer than doing so without it.

Tesla also has been rolling out an upgraded suite of assistance features on a limited basis, a system it calls “full self-driving.”

“Autopilot and full self-driving capability are intended for use with a fully attentive driver, who has their hands on the wheel and is prepared to take over at any moment,” Tesla says on its website, noting that the features don’t make the vehicle autonomous.

Some safety advocates have said that the company doesn’t do enough to keep drivers from depending too much on the features or using them in situations for which they aren’t designed. They also have criticized the company for the language it uses to describe its features, saying that terms such as “Autopilot” and “full self-driving” risk giving drivers a false sense of the vehicle’s abilities. (SD-Agencies)