Tesla has yet to apply for regulatory permits it needs to operate driverless taxis in California, two state regulators said on Thursday, a day after CEO Elon Musk said the company would expand its robotaxis to the San Francisco Bay Area within two months.

San Francisco is likely to prove a more challenging area for Tesla’s self-driving systems. The city is significantly more densely populated and has more challenging roads, largely due to its extreme topography and steep streets.