One of Google’s self-driving car prototypes was involved in a collision while navigating a public road, the company said Thursday. The Lexus SUV prototype was rear-ended in Mountain View, California, on July 1 with three Google employees in the car. The employees complained of minor whiplash symptoms and were treated at a hospital. The driver of the other car also complained of neck and back pain. More than 20 Google prototypes are being tested on public roads. The collision was the 14th accident in six years and part of around 1.9 million miles of testing, Google said. In 11 of those 14, the car was rear-ended, according to the company.