No one was hurt, yet.
The self-driving cars roaming around California have already been involved in a few fender benders.
An investigation conducted by the Associated Press reports that since last September, when the state started issuing permits for companies to test out the autonomous vehicles on public roads, four of the 48 cars have gotten into minor accidents.
The accidents were reported to the state's Department of Motor Vehicles. They were tight-lipped about specifics because California law stipulates that collision reports be kept confidential, according to the AP.
The AP, however, dug up information about the four incidents. In two of the accidents, the car was in control while in the other two incidents, a human was driving the vehicles. All of which happened when the cars were going under 10 miles per hour. A person still must remain behind the wheel at all times.
Google, who is spearheading an ambitious self-driving project, had three of its specially equipped Lexus SUVs involved in the collisions. Delphi Automotive had the other accident. Regardless, the two companies claimed not to be at fault and told the AP that the accidents "were minor."
Notably, this marks the first time that driverless cars have been reported to be involved in accidents.
Publicly, at least. The future of these autonomous vehicles gliding down our streets operate under the assumption that they're safe alternatives compared to their human-operated counterparts.
Update: Chris Urmson, director of Google's driverless car team, wrote a blog post at Medium providing a bit more information. He says Google's cars have been involved in at least 11 accidents total, mostly when it was rear-ended.
"Even when our software and sensors can detect a sticky situation and take action earlier and faster than an alert human driver, sometimes we won't be able to overcome the realities of speed and distance; sometimes we'll get hit just waiting for a light to change," he wrote.
"Over the 6 years since we started the project, we've been involved in 11 minor accidents (light damage, no injuries) during those 1.7 million miles of autonomous and manual driving with our safety drivers behind the wheel, and not once was the self-driving car the cause of the accident," he added.
Motherboard has previously reported that the only way for driverless cars to be 100 percent safe is if they accurately predict the future—say by anticipating when someone is going to jump in front of the car.
French computer scientist Thierry Fraichard explained to Motherboard in April 2014 that only way a car can avoid a collision is that it needs to know every single thing that's going to happen in the future and learn how to avoid any trouble spots.
"If you could make sure the car won't break or your [car's] decisions are 100 percent accurate, even if you have the perfect car that works perfectly, in the real world there are always unknown moving obstacles," Fraichard told Motherboard. "Even if you're some kind of god, it's impossible. It's always possible to find situations where a collision will happen."
For now, at least, these situations are happening at slow speeds.