Waymo is recalling software across all 3,791 driverless taxis after an unoccupied robotaxi entered a flooded road in San Antonio on April 20. The National Highway Traffic Safety Administration said the software could allow vehicles to drive into standing water on high-speed roadways, raising the risk of crashes and injuries. The company paused public service in San Antonio while working on fixes.

Chris Bonelli, a Waymo spokesman, said the company identifies areas of improvement after incidents and is refining extreme weather operations. All 3,791 vehicles in the fleet are affected. The software fix can be deployed when cars return to depots for routine maintenance, so taxi service won't be interrupted elsewhere.

The recall adds to mounting safety concerns around autonomous vehicles. Waymo faces federal investigations into traffic violations and previously recalled software in December after robotaxis illegally passed stopped school buses. Investors watching the company closely will be watching how quickly it can restore confidence in its operations.