The National Highway Traffic Safety Administration (NHTSA) has opened an official investigation into Ford’s BlueCruise advanced driver-assistance software after it’s been linked to multiple fatalities while in use. It includes two 2024 incidents that the National Transportation Safety Board is also investigating — one in San Antonio and another in Philadelphia.

The NHTSA’s Office of Defects Investigation notes that the Ford vehicles involved in the fatal crashes hit stationary objects including vehicles stopped in a driving lane on the highway. Ford’s BlueCruise enables hands-free driving on pre-mapped highway roads and uses cameras to both watch drivers and keep its vehicles in the lane. The system was introduced in 2021 in vehicles like the Mustang Mach-E, which is the model cited in both incidents.

The official investigation into the crashes involving BlueCruise comes only days after a new NHTSA probe was opened to determine if Tesla’s Autopilot driver-assistant software recall did enough to increase driver engagement and protect lives. At the same time, the NHTSA also determined Tesla’s Autopilot and its “Full Self-Driving” feature that promises the vehicles can achieve autonomous driving under supervision aren’t keeping drivers engaged enough.

Ford told TechCrunch that it’s “working with NHTSA to support its investigation.” Regulators will look to determine if Ford’s driver monitor system does enough to keep users engaged while BlueCruise and Ford’s Co-Pilot360 (a precursor to BlueCruise on previous models) software are active.