That was quick. We’ve just heard about Uber’s self-driving Volvo cars arriving in San Francisco, and now the state of California (where SF is in) has shut down the ride-sharing company’s testing of self-driving cars in the Golden State, AFP reports.

It’s all about permits, and Uber launched its test without the required permit from the state. Twenty companies have been approved to test a total of 130 vehicles, the California Department of Motor Vehicles (DMV) pointed out. In a letter to Uber, DMV counsel Brian Soublet said the permit is required in part to protect public safety.

“It is illegal for the company to operate its self-driving vehicles on public roads until it receives an autonomous vehicle testing permit. It is essential that Uber takes appropriate measure to ensure safety of the public. If Uber does not confirm immediately that it will stop its launch and seek a testing permit, DMV will initiate legal action,” he wrote. Uber was not immediately available to comment on the department’s action.

A consumer protection organisation based in Santa Monica, Consumer Watchdog, had condemned the Uber pilot project earlier this week. “Consumer Watchdog today called on San Francisco police to impound Uber’s robot cars operating without a permit on city streets and asked City Attorney Dennis Herrera to file criminal charges against Uber CEO Travis Kalanick,” it said in a statement, citing reports of Uber’s self-driving cars running red lights in San Francisco.

Uber rolled out its autonomous cars in San Francisco after an initial pilot earlier this year in Pittsburgh, Pennsylvania. “We’re excited to start operating in our hometown of San Francisco with Volvo XC90s, our first cars built in partnership with a major auto-manufacturer,” the RM268 billion company said in a statement.