A Tesla electric car that “no one” appeared to be driving crashed late Saturday in Texas, erupting into flames and killing the two passengers, according to local authorities.

One victim was found in the front passenger seat of a 2019 Model S, and the other was in the rear, Harris County Precinct 4 Constable Mark Herman said in a telephone interview. The car ran into a tree in the Carlton Woods subdivision near The Woodlands after traveling fast and failing to navigate a turn.

The position of the victims, statements and other physical evidence suggest that “no one was driving the vehicle at the time of impact,” Herman said. “It’s still under investigation.”

Herman said his office is coordinating with federal authorities, without specifying which ones, and did not know whether the Autopilot feature was engaged. It took more than 30,000 gallons of water to extinguish the fire, which burned for four hours, he added.

Tesla did not immediately respond to a request for comment Sunday.

Federal officials have criticized Tesla for fire risks related to the battery packs in its cars and for what they call insufficient effort to keep drivers from using the driver-assist function inappropriately. In a hearing last year, the National Transportation Safety Board’s chairman said “it’s time to stop enabling drivers in any partially automated vehicle to pretend that they have driverless cars.”

Tesla CEO Elon Musk has defended the safety record of his company’s vehicles. Last week, he shared a report on Twitter, saying that a Tesla with Autopilot engaged is now approaching a “10 times lower” chance of a crash than an average vehicle.