The driver of a Tesla Model S who crashed into a fire truck on a California freeway says he was using Autopilot at the time of the accident, and so far, Tesla isn’t refuting this claim.

“Autopilot is intended for use only with a fully attentive driver,” a Tesla spokesperson said when asked to confirm the driver’s assertion that he was using Autopilot when his vehicle smashed into the back of a fire engine at 65 mph. Tesla has the ability to examine a vehicle’s data logs to determine whether Autopilot is engaged during certain incidents.

“Autopilot is intended for use only with a fully attentive driver”

Now, Bloomberg is reporting that the federal government is “gathering information” on the accident, but has not yet decided to formally open an investigation. A spokesperson for the National Traffic Safety Board did not immediately respond to a request for comment, while a Tesla spokesperson declined to comment.

There have been a handful of reports of Tesla vehicles involved in accidents with Autopilot engaged. The most prominent — and tragic — occurrence was in 2016 when a Florida man named Joshua Brown was killed after his Model S smashed into the side of a truck. Brown had been using Autopilot at the time, but the NTSB ruled that Tesla was not complicit in the crash. A preliminary report issued in July 2016 stated his vehicle was going 74 mph at the time of the crash on a highway with a 65 mph speed limit.

While the board faulted Brown for not paying attention in the seconds before the crash, they noted Autopilot did an inadequate job of detecting other traffic and did not inform the driver early enough to allow for sufficient reaction time. In response, Tesla said it would be “extremely clear” about communicating to its customers the need to stay attentive while using Autopilot.

The conundrum, of course, is that advanced driver assistance systems like Autopilot can often lull drivers into a state of inattentiveness by virtue of their effectiveness. Tesla’s Autopilot was never intended to be a hands-free system, but some drivers abused the system by uploading videos of themselves reading newspapers while driving down the highway. In 2016 Tesla tweaked the software to require drivers to keep their hands on the steering wheel or get locked out of the system. (Since then, some drivers use oranges wedged under the wheel to mimic the pressure of the human hand.)

GM claims to solve this problem by monitoring the driver’s eye movements with infrared cameras mounted on the steering column. Super Cruise, GM’s semi-autonomous driving system, will deactivate if drivers turn their gaze away for more than several seconds, which some experts have praised as an effective way to keep the driver engaged.

Correction: Tesla’s Autopilot was never intended to be a hands-free system. A previous version of this story misstated that fact.