General Motors’ autonomous vehicle division, Cruise LLC, has recalled all 300 of its vehicles following a crash that it calls “anomalous.” It has now released a software update that it believes will prevent the issue from reoccurring.

The accident occurred on March 23, 2023, according to documents filed with the National Highway Traffic Safety Administration, when a Cruise vehicle with no occupants rear-ended a San Francisco Municipal Transit Authority articulated bus as it was leaving a stop.

“In this incident, the [Autonomous Driving System] initially perceived both sections of the bus as the bus was pulling out of a bus stop in front of the AV,” writes Cruise. “As the bus proceeded forward into the AV’s lane of travel, the rear section of the bus obstructed the front section. Shortly thereafter, the bus began decelerating.”

Read: Cruise Recalls And Updates Software On Autonomous Vehicles After Crash

GM’s Cruise Recalls Autonomous Vehicles Following Crash Into Articulated Bus

As the bus slowed, the Cruise vehicle, dubbed Souffle, incorrectly determined that the bus was still moving forward. The determination was made because it couldn’t “see” the front of the bus, and simply anticipated that it was continuing on and that the rear section would follow. Souffle started braking too late, as it realized that the bus wasn’t moving, and crashed into it.

In a tweet from that day, Cruise said that no injuries were reported as a result of the collision. It also claims that no other incidents have occurred as a result of the programming flaw that allowed this incident to happen.

Cruise says that the issue is “related to the prediction of the unique movements of articulated vehicles in rare circumstances.” It has, therefore, recalled the vehicles and updated their software to address the issue and prevent another collision from happening. The software update was rolled out on March 25, 2023, two days after the crash occurred.