The senators want to know where testing is occurring, how companies determined if the self-driving tech was safe for public roads and whether the technology relies on internal sensors or external inputs and more. Copies of the letter were sent to the US offices of BMW, Daimler Trucks, Fiat Chrysler, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Kia, Mazda, Mercedes-Benz, Mitsubishi, Nissan, Subaru, Tesla, Toyota, Volkswagen, Volvo, Amazon, Apple, Intel, Lyft, NVIDIA Corporation, Uber and Waymo.

"This latest fatality has raised many questions about the processes companies have in place to guard public safety when testing this type of technology on public roads," the senators wrote in the letter sent to Uber. "Although we understand that Uber and several other AV companies have temporarily halted vehicle testing, we would like to know more about your company's protocols for test-driving AVs on public roads and how they will be adjusted in light of the recent tragedy."