Google self-driving car has a bingle

One of Google's self-driving car prototypes has been involved in an injury accident for the first time, the tech giant reports.

A Lexus SUV outfitted with sensors and cameras was rear-ended in Google's home city of Mountain View, where more than 20 prototypes have been self-manoeuvring through traffic.

The three people on board complained of minor whiplash, were checked out at a hospital and cleared to go back to work following the July 1 collision, Google said on Thursday. The driver of the other car also complained of neck and back pain.

In California, a person must be behind the wheel of a self-driving car being tested on public roads to take control in an emergency. Google typically sends another employee in the front passenger seat to record details of the ride on a laptop. In this case, there was also a back seat passenger.

An accident report filed by Google with the California Department of Motor Vehicles states:

Google's SUV was going about 15mph (24.14km/h) in self-driving mode behind two other cars as the group approached an intersection with a green light.

The first car slowed to a stop so as not to block the intersection - traffic on the far side was not moving. The Google car and the other car in front of it also stopped.

Within about a second, a fourth vehicle rear-ended the Google car at about 17mph (27.35km/h). On-board sensors showed the other car did not brake.

Local police responded, but did not file an accident report.

Google has been a pioneer of self-driving technology, which it believes will be safer and more efficient than human-driven cars. This was the 14th accident in six years and about three million kilometres of testing, according to the company.

Google has said its car has not caused any of the collisions - though in 2011 an employee who took a car to run an errand rear-ended another vehicle while the Google car was out of self-driving mode.