Waymo is recalling its U.S. fleet of robotaxis after one of the autonomous vehicles was swept away when it drove into floodwaters in San Antonio. The software recall stems from an incident during severe weather April 20, when a Waymo vehicle "encountered an untraversible flooded section of a roadway," the company told the National Highway Traffic Safety Administration. Though the vehicle detected the flooded road, it continued into floodwaters at reduced speed. Waymo said the vehicle was unoccupied and that there were no injuries, but the incident prompted the company to review similar scenarios and issue an interim update to its self-driving software. It also suspended operations in San Antonio, a city prone to flooding and where the April 20 incident was the second recent local instance of a Waymo vehicle struggling with flooding. NHTSA said Waymo also has temporarily narrowed its operating scope to increase weather-related restrictions and updated its service-area maps while it works on a permanent remedy. Outside San Antonio, passengers should see little or no impact. "We are working to implement additional software safeguards and have put mitigations in place, including refining our extreme weather operations during periods of intense rain, limiting access to areas where flash flooding might occur," Waymo said in a statement. The company said Tuesday it had resumed autonomous operations in San Antonio after its longest-ever shutdown but is still not serving riders. The recall affects 3,791 vehicles equipped with the Alphabet Inc.-owned company's fifth- and sixth-generation automated-driving system, according to documents posted to the NHTSA website. Waymo says its autonomous fleet has about 3,800 vehicles. The April 20 incident occurred when a robotaxi was overtaken by Salado Creek floodwaters. Crews recovered the vehicle four days later along the Greenway Trail system near Pletz County Park. Neither Waymo nor city officials have