One of Uber’s driverless cars in Pittsburgh was involved in a crash Monday morning, forcing the ride-hailing firm to temporarily suspend its autonomous vehicle fleet while it investigates the incident.



Only Uber employees were inside the self-driving vehicle when it crashed, the company told the Tribune-Review, and no serious injuries were reported.



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But Uber grounded its driverless vehicle fleet following the incident. Self-driving Uber vehicles, which still have a driver behind the wheel, were reportedly back on the road and picking up passengers by 11 a.m.Pittsburgh was the first city where Uber began testing its driverless car program, which was rolled out last fall and has experienced some hiccups.A driverless Uber was also involved in a crash in Tempe, Ariz., earlier this year, which forced the company to suspend its autonomous vehicle operations. But police found that the Uber was not at fault in that incident.