Mitchell Weston, chief investigator at the Harris County Fire Marshal’s Office, said that while the batteries are “generally safe,” impacts at high speeds can result in “thermal runaway,” which causes an “uncontrolled contact” between different materials in the batteries.

Thermal runaway can lead to fires, as well as “battery reignition,” even after an initial fire is put out, the safety board warned in its report. Mitsubishi Electric warns that “thermal runaway can lead to catastrophic results, including fire, explosion, sudden system failure, costly damage to equipment, and possibly personal injury.”

The fire marshal’s office was investigating the fire in the crash, a spokeswoman said. Constable Herman said his department was working with the federal authorities to investigate.

He said that law enforcement officials had been in contact with Tesla on Saturday for “guidance on a few things” but declined to discuss the nature of the conversations.

Tesla, which has disbanded its public relations team, did not respond to a request for comment.

Elon Musk, Tesla’s chief executive, earlier on Saturday had promoted a recent safety report from the company, writing on Twitter that “Tesla with Autopilot engaged now approaching 10 times lower chance of accident than average vehicle.”

Tesla, which on its website calls Autopilot the “future of driving,” says the feature allows its vehicles to “steer, accelerate and brake automatically within its lane.” However, it warns that “current Autopilot features require active driver supervision and do not make the vehicle autonomous.”

In 2016, a driver in Florida was killed in a Tesla Model S that was in Autopilot mode and failed to brake for a tractor-trailer that made a left turn in front of it.