Tesla told U.S. regulators that its answers to questions on the safety of its robotaxi deployment in Texas are confidential business information and should not be made public, according to a letter released on Monday.

The automaker deployed a small fleet of self-driving taxis in Austin, Texas, on Sunday, marking the first time its cars have carried paying passengers without human drivers. The rides were being offered for a flat fee of $4.20 in a limited zone.

The company's first robotaxi rides are happening. However, a human "Tesla Safety Monitor" will accompany the first riders.