Two Senate Democrats are urging federal regulators to take “corrective actions” against Tesla to prevent further misuse of the company’s advanced driver assist feature. The request comes in the aftermath of a fatal crash in which two men from Texas were killed after their Tesla Model S crashed with no one in the driver’s seat.

In a letter sent to National Highway Traffic Safety Administration Acting Administrator Steven Cliff, Senators Ed Markey (D-MA) and Richard Blumenthal (D-CT) implored the agency to determine the exact cause of this recent crash to “better inform” future legislation around advanced driver assist systems like Tesla’s Autopilot.

“We strongly urge you to conduct a complete investigation into Saturday’s fatal Tesla vehicle crash and develop recommendations for improving automated driving and driver assistance systems,” Markey and Blumenthal write. “We look forward to working with you and the NTSB to implement policy changes that stop these preventable deaths from occurring and save lives.”

A special crash team from NHTSA is investigating the crash, as well as investigators from the independent National Transportation Safety Board. On Monday, NHTSA said the agency is coordinating with local law enforcement to learn more about the incident and will “take appropriate steps” when investigators have gathered more information.

The incident took place at 9PM local time in Spring, Texas. According to KHOU in Houston, investigators are “100 percent certain” that no one was in the driver’s seat at the time of the crash. Minutes before the crash, the wives of the men were said to overhear them talking about the Autopilot feature of the vehicle, which was a 2019 Tesla Model S, according to The New York Times. The two victims were identified as Everette Talbot, 69, and William Varner, 59, a prominent local anesthesiologist.

It’s not clear what direction NHTSA’s investigation will take. In the past, the agency has been criticized for misrepresenting Autopilot’s safety record and for giving the company a pass when it comes to the possibility that its customers could misuse the technology in its vehicles. NHTSA recently disclosed that it has opened 27 investigations into crashes of Tesla vehicles, 23 of which remain active. Tesla CEO Elon Musk recently tweeted that “NHTSA is great.”

NTSB, on the other hand, has proven more willing to point fingers at Musk’s company. An NTSB investigation into the 2018 death of a Tesla owner in California said Autopilot was partly to blame. Musk has been much more hostile toward the agency, at one point hanging up on the chairman of NTSB.

Tesla didn’t respond to a request for comment, likely because the company has dissolved its press office and typically doesn’t respond to media requests anymore. In a recent tweet, Musk claimed that “data logs recovered so far” indicate that Autopilot was not engaged, nor had the vehicle owner purchased the company’s “Full Self-Driving” option that may have allowed the use of Autopilot on local roads.

Tesla owners have shown that Autopilot can be used on roads without lane markings, and Consumer Reports recently conducted a test proving that Tesla’s vehicles can easily be tricked into thinking there is someone behind the wheel, even when there’s not.