1 . An Uber self-driving car hit and killed a woman crossing the street in Arizona, U.S., police said on Monday, marking the first death caused by an autonomous vehicle and a potential blow to the technology expected to transform transportation.

The ride services company said it was delaying North American tests of its self-driving vehicles, which are currently going on in Arizona, Pittsburgh and Toronto.

So-called robot cars, when fully developed by companies including Uber, are expected to thoroughly cut down on motor vehicle deaths and create billion-dollar businesses. But Monday's accident highlighted (凸显) the possible challenges ahead for the promising technology as the cars face real-world situations involving real people.

"This catastrophic accident highlights why we need to be exceptionally cautious when testing and applying autonomous vehicle technologies to public roads," said Edward Markey, a member of the transportation committee, in a statement. "Elaine Herzberg, 49, was walking her bicycle outside the crosswalk on a four-lane road in the Phoenix suburb of Tempe at about 10 p.m. MST Sunday when she was struck by the Uber vehicle traveling at about 65 kilometers per hour," police said. The car was in autonomous mode with an operator behind the wheel. U.S. federal safety officials were sending teams to investigate the crash. Canada's transportation ministry in Ontario, where Uber conducts are being tested, also said it was reviewing the accident.

"Uber and Waymo on Friday urged Congress to pass a law to speed the introduction of self-driving cars into the united states. However, some congressional (国会) representatives have blocked the legislation over safety concerns, and Monday's death could hamper passage of the bill, "congressional assistants said Monday.