Uber Technologies Inc has suspended its self-driving car programme in the United States after one of its vehicles was involved in an accident in Arizona’s Tempe city on Friday. A spokesperson for the police said the crash took place after another car “failed to yield” to the Uber vehicle at a left turn, the BBC reported on Saturday.

Tempe police information officer Josie Montenegro told Bloomberg that there was a person behind the wheel in Uber’s Volvo self-driving SUV when the incident occurred, but it was “uncertain at this time whether they were controlling the vehicle at the time of the collision”. There was no passenger in the backseat when the accident took place.

The ride-hailing company’s autonomous vehicles always have someone in the driver’s seat so they can take over the controls when needed. An Uber spokesperson said they would not resume the programme till a thorough investigation is conducted.

The company had been testing its autonomous vehicles in Pittsburgh, San Francisco and Arizona. While the California Department of Motor Vehicles had banned its self-driving cars from the streets of San Francisco in December, it has now paused its operations in the other states, as well.