The NHTSA has launched an investigation into BlueCruise, Ford’s hands-free driving system, after two collisions that each resulted in a fatality.

According to the NHTSA, there were two incidents involving the Ford Mustang Mach-E, both of which resulted in a fatality.

The Office of Defects Investigation (ODI) has received notice of two (2) incidents involving Ford Mustang Mach-E vehicles that collided with stationary vehicles, which were located within the travel lanes of controlled-access highways. Both collisions occurred during nighttime lighting conditions, and each incident resulted in at least one fatality. The incident reports received by NHTSA were submitted under Standing General Order 2021-01 (SGO). ODI’s initial investigation of both incidents confirmed that BlueCruise was engaged in each of the subject vehicles immediately prior to the collision.

The investigation is the latest evidence of the challenges automakers are facing in designing and deploying true self-driving automobiles.