One of Google’s self driving test cars has hit a bus, in what is probably the first collision caused by the search giant’s test cars. To date all collisions so far have either been caused by other vehicles or by people driving the cars. The party to blame has still not been determined and Google will meet with the California DMV.

In a statement, Google said:

“We clearly bear some responsibility, because if our car hadn’t moved, there wouldn’t have been a collision. That said, our test driver believed the bus was going to slow or stop to allow us to merge into the traffic, and that there would be sufficient space to do that.”

Google releases a report with details of its self driving car tests every month. The report read:

“The Google AV [autonomous vehicle] test driver saw the bus approaching in the left side mirror but believed the bus would stop or slow to allow the Google AV to continue,” the report read.

“Approximately three seconds later, as the Google AV was re-entering the centre of the lane it made contact with the side of the bus.

“The Google AV was operating in autonomous mode and travelling at less than two mph, and the bus was travelling at about 15mph at the time of contact.”

Google has also refined its algorithm after the incident:

“From now on, our cars will more deeply understand that buses (and other large vehicles) are less likely to yield to us than other types of vehicles, and we hope to handle situations like this more gracefully in the future.”

Were the DMV to find the self driving car at fault for the collision, it would be a massive setback for the program just after the NTSB ruled that it would consider the self driving computer the same as a human driver.