Ms. Kohler said on Saturday that Uber was suspending the testing of its self-driving vehicles in Arizona, pending the results of the investigation of the accident. She said Uber had also suspended testing in Pittsburgh and San Francisco for the day, and possibly longer.

The news of the accident was first reported by ABC-15, an Arizona affiliate station.

The incident comes at a difficult time for Uber, which for the last two months has fielded multiple crises involving the company’s workplace culture and business practices. Earlier in March, The New York Times reported the existence of a tool called Greyball, which Uber engineers used to skirt authorities cracking down on Uber drivers worldwide. In addition, Travis Kalanick, Uber’s chief executive, was forced to apologize for his aggressive behavior after Bloomberg published video of a verbal altercation he had with an Uber driver.

Although Uber was not at fault in the Arizona accident, the incident is problematic for the company, a start-up based in San Francisco, which has gone head-to-head with regulators as it has tried to persuade cities to allow public testing of its autonomous vehicles. Google, General Motors and Ford Motor Company are all testing autonomous vehicles in California and have registered to do so.

After a successful introduction of the autonomous vehicle program in Pittsburgh last year, Uber ran into obstacles in December, when it tried to begin the testing of self-driving vehicles in San Francisco without registering for permits. The permits require companies to disclose the number of accidents their vehicles have been involved in.

Shortly after the San Francisco testing began, one of Uber’s self-driving cars failed to recognize a stoplight and sailed through a crosswalk. The car was driving itself at the time, according to internal documents reviewed by The Times.