News of the incident has been confirmed by the state's road authority, which said that the modified Lexus RX450h was rear-ended by a human driver, who was behind the wheel of a Nissan Leaf.
An incident description explained: "An Apple test vehicle in autonomous mode was rear-ended while preparing to merge onto Lawrence Expressway South from Kifer Road.
"The Apple test vehicle was travelling less than 1mph waiting for a safe gap to complete the merge when a 2016 Nissan Leaf contacted the Apple test vehicle at approximately 15mph.
"Both vehicles sustained damage and no injuries were reported by either party."
Meanwhile, Toyota recently announced it is set to invest as much as $500 million in Uber.
The Japanese manufacturer - which is one of the world's best-known car brands - confirmed the investment, saying that its long-term ambition is to develop self-driving vehicles.
Shigeki Tomoyama, executive vice president of Toyota Motor Corporation, explained: "This agreement and investment marks an important milestone in our transformation to a mobility company as we help provide a path for safe and secure expansion of mobility services like ride-sharing."