The U.S. auto regulator said Monday it has opened a preliminary investigation into Ford Motor's hands-free driving technology BlueCruise after being informed of two incidents involving Mustang Mach-E cars that collided with stationary vehicles.

The National Highway Traffic Safety Administration's Office of Defects Investigation (ODI) opened the evaluation to investigate BlueCruise, which provides partial driving automation with the expectation that the driver actively supervises its performance.

Both the collisions occurred during "nighttime lighting conditions," and each resulted in at least one fatality, according to the NHTSA.

ODI's initial investigation of the incidents confirmed BlueCruise's engagement in each of the vehicles right before the collision.

BlueCruise is only available on certain roadways and uses a camera-based driver monitoring system to determine driver attentiveness.

The investigation will evaluate the system's performance on the dynamic driving task and driver monitoring, the NHTSA said.

Ford Motor did not immediately respond to a request for comment.

BlueCruise was introduced in model year 2021 vehicles and at present is there in a range of Ford and Lincoln vehicles.

Last week, the NHTSA opened a probe into whether Tesla's recall of more than 2 million vehicles announced in December to install new Autopilot software updates was adequate following a series of crashes.

The NHTSA opened the investigation after receiving reports of 20 crashes involving vehicles that had the new Autopilot software updates.