Following a collision with a driverless car in Tempe, Ariz., ride-sharing behemoth Uber Technologies is suspending its autonomous car programs in Pittsburgh, Tempe and San Francisco.

Uber is one of several high-profile companies racing to put the world's first 100% autonomous vehicle on the road for consumers to purchase, including Tesla, Google and Toyota. The unicorn, valued at roughly $63B, launched the program in Pittsburgh in September, testing an unspecified number of autonomous Ford Fusions last year.

Uber had just put its autonomous vehicles back on the streets in San Francisco; earlier this year, it won a battle with the California Department of Motor Vehicles over proper vehicle permits that had forced it to temporarily stop testing.

The accident occurred Friday, March 24. A Volvo XC90 SUV was in self-driving mode and was hit and overturned by a regular vehicle that failed to stop, the Wall Street Journal reports. Tempe Police said the fault did not lie with Uber, but a company spokeswoman said the firm will continue to look into the incident. There were no injuries from the accident.

This is a major setback for Uber, which has been investing heavily in technology to limit accidents and fatalities.