Startup technology firm Pony.ai has issued a recall for some versions of its autonomous driving system software after a crash in California, according to U.S. regulators.

This recall includes three vehicles that have been repaired, Pony.ai told the National Highway Traffic Safety Administration (NHTSA), according to a report by Reuters. The specific software (with an issue) had been used by the three vehicles.

NHTSA said that this is the first recall of an automated driving system, according to the report.

On Oct. 28, a Pony.ai vehicle (that had been in autonomous mode) hit a street sign on a median after turning right. This incident led California to suspend the company’s driverless testing permit.

Pony.ai cooperated with NHTSA’s inquiry about the incident and suspended its testing program to do a detailed review, according to the report. NHTSA thought the software had a safety defect and requested Pony.ai to conduct a recall, Pony.ai said in a filing.

Pony.ai updated the software code and the three affected vehicles have been repaired, according to the report.

"Whether the vehicle is operated by a human driver or an automated driving system, the need to protect roadway users remains the same," NHTSA Deputy Administrator Steven Cliff said in a statement. "As this first recall of an automated driving system underscores, NHTSA will ensure that vehicle manufacturers and developers prioritize safety while they usher in the latest technologies."