The National Highway Traffic Safety Administration (NHTSA) is currently investigating Amazon's Zoox after two robotaxi crashes.

• The National Highway Traffic Safety Administration is investigating two accidents involving Amazon-owned Zoox autonomous vehicles.
• Two Toyota Highlanders with Zoox's automated self-driving technology suddenly braked, causing motorcyclists to collide with the vehicles.
• The agency's probe covers about 500 vehicles.

Zoox, an autonomous robotaxi venture owned by -, is under investigation by U.S. safety regulators after two of its SUVs experienced sudden braking and were rear-ended by motorcyclists.

The National Highway Traffic Safety Administration launched an investigation on Monday following two Toyota Highlanders with Zoox's automated self-driving braking system unexpectedly stopping, resulting in minor injuries to motorcyclists involved in collisions with the Zoox vehicles.

The NHTSA confirmed that each Zoox car involved in the incidents was operating in autonomous mode. Both collisions occurred during the daytime and within the operational design limits of Zoox's autonomous system.

The investigation by the agency centers on the performance of Zoox's automated driving system, particularly its behavior near crosswalks and in other similar rear-end collision scenarios, with a focus on approximately 500 vehicles.

Representatives from Zoox did not immediately respond to a request for comment.

In 2020, Amazon acquired Zoox for $1.2 billion. Zoox, which operates as a standalone unit within Amazon, has been developing an electric, fully driverless vehicle for ride-hailing. The company has been testing its robotaxis in Las Vegas and Foster City, and in March announced it was expanding its operating routes to include a larger area, faster speeds, nighttime driving, and light rain conditions.

NHTSA is conducting a separate investigation into Zoox's self-certification in 2022 that its robotaxi met federal safety standards.