NHTSA opened a probe this summer into Autopilot over crashes involving a dozen parked emergency vehicles while the system was activated. The agency also asked Tesla and other car-makers, along with manufacturers of self-driving vehicles, to report on many crashes involving autonomous and advanced-driver assistance systems within a day of learning of the incidents.

U.S. auto safety regulators are investigating Tesla Inc.'s advanced driver-assistance system known as Autopilot after a series of crashes involving emergency vehicles. The National Highway Traffic Safety Administration said in a document made public Monday that it had identified 11 crashes since early 2018 in which a Tesla vehicle using the company's driver-assistance system struck one or more vehicles involved in an emergency-response situation. NHTSA has been looking more closely at advanced driver-assistance systems such as Autopilot as they have become more ubiquitous and safety concerns have grown. The agency recently began requiring companies to regularly report crashes involving advanced driver-assistance or automated driving systems to the agency.