Waymo is recalling the autonomous driving software in 3,791 of its robotaxis after a vehicle drove onto a flooded road it should have avoided, according to documents filed with federal safety regulators.

The recall affects vehicles operating on Waymo's fifth and sixth generation autonomous driving systems, the Alphabet-owned company disclosed in filings with the National Highway Traffic Safety Administration.

The safety issue came to light after an unoccupied Waymo robotaxi encountered what the company described as an "untraversable flooded section" of road. The incident revealed a flaw in the software's ability to properly assess and avoid flooded roadways that pose risks to vehicle operation.

Waymo, which operates one of the most advanced commercial robotaxi services in the United States, has been expanding its autonomous vehicle operations in several cities. The company's vehicles use sophisticated sensor systems and artificial intelligence to navigate roads without human drivers.

The recall involves a software update to address the flooding detection issue. Waymo has not disclosed when the flooding incident occurred or provided details about any potential damage to the vehicle involved.