Google says one of its self-driving cars has been involved in an injury accident for the first time.

The tech giant disclosed Thursday that one of its SUVs was rear-ended in its home city of Mountain View, and the three people on board complained of minor whiplash. All were released from the hospital soon after the July 1 collision.

In California, a person must be behind the wheel of a self-driving car prototype being tested on . There were also two passengers.

According to Google, its SUV was stopped near an intersection when another car hit it at about 17 mph. On-board sensors showed the other car did not brake.

Google Inc. has pioneered self-driving technology. It says that in six years of testing, its cars have been hit 14 times.