US auto safety regulators said on Tuesday they were opening a probe into 50,000 Tesla Model X vehicles after receiving two complaints reporting front seat belt failures.

The National Highway Traffic Safety Administration (NHTSA) told Reuters the preliminary evaluation covered 2022-2023 model year vehicles over reports of failures of the front seat belt to remain connected to the seat belt anchor pretensioner while driving.

Both newer vehicles had insufficiently connected anchor linkages and neither incident involved a vehicle collision with occupants wearing seat belts, the agency told the news agency.

Tesla, which has disbanded its press office, did not respond to Reuters’ request for comment.

In one complaint from Larkspur, California, a Tesla was moving at around 10 to 15 miles per hour and the auto braking system activated when the driver’s door on a large truck parked on the side of the street opened unexpectedly.

“With the sudden deceleration, my upper body flung forward and the force of my weight caused the seat belt anchor on the lower seat to detach completely,” a complaint filed with the NHTSA reportedly said.

After the NHTSA opens a preliminary evaluation, it must decide whether to upgrade it to an engineering analysis before it can demand a recall, Reuters noted.