07:55 AM EDT, 05/13/2024 (MT Newswires) -- Amazon.com's ( AMZN ) Zoox automated driving system is under preliminary investigation by the US National Highway Traffic Safety Administration over unexpected braking that led to two rear-end collisions, causing injuries to two motorcyclists, the agency said in a document Monday.

Both incidents occurred during daytime lighting conditions and involved a Toyota Highlander equipped with a Zoox automated driving system, according to the agency.

The preliminary investigation, which was opened Friday, will evaluate the Zoox automated driving system's performance, particularly in relation to collisions, along with its behavior in crosswalks around vulnerable road users and in other similar rear-end collision scenarios, the NHTSA document showed.

Amazon ( AMZN ) acquired Zoox in June 2020 for more than $1 billion, according to documents seen by Reuters.

Amazon ( AMZN ) did not immediately reply to MT Newswires' request for comment.

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