A Twitter user has shared photos of an Uber self-driving car flipped onto its side after an apparent crash in Tempe, Arizona. The photos also show another seriously damaged vehicle that appears to have been involved.
Uber has confirmed the crash, and the legitimacy of the photo, to Bloomberg.
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There’s little other information about the incident yet—perhaps most crucially, whether the car was actually in self-driving mode during the crash. Fortune has reached out to Uber and will update this story with any new information.
If the vehicle was operating in self-driving mode at the time of the crash, it would provide another major sign that Uber’s self-driving car program is not going well. In February, company sources speaking to the New York Times said that self-driving Ubers had failed to detect multiple red lights during tests in San Francisco. And earlier this month, leaked company documents showed that Uber’s vehicles required very frequent intervention from human monitors.
Uber leadership have frequently described the development of self-driving car technology as crucial to the company’s long-term strategy. Uber drivers have become increasingly vocal and active in demanding better pay and working conditions, which could put substantial further pressure on the company’s already deep-in-the-red bottom line.