City Sightseeing will likely face fines for violating state regulations and could have its operating license revoked after last week's tour bus crash in San Francisco's Union Square that left 20 injured.
Investigators found the double-decker bus involved in the crash was not registered with the California Public Utilities Commission, which is required of any company operating that type of vehicle.
Such companies are required to contact the CPUC within 10 days of a bus going into service. Regulators on Thursday said City Sightseeing failed to fulfill the requirement.
A California Highway Patrol inspection is also required before the vehicle hits the streets. State officials said in this case that never happened.
Maintenance records obtained from the CHP show the bus is not among City Sightseeing's list of vehicles previously inspected. As a result, the company could face multiple violations.
If fines total more than $20,000, the state will launch a formal civil investigation.
"We will be taking a close look," said Christine Falvey with the San Francisco Mayor's Office. "We'll be relying on our state partners where this is regulated, but the use of our streets is obviously the city's responsibility as well as we'll be looking at anything that will make the streets safer."
San Francisco Mayor Ed Lee has also committed the city's resources to state investigators and is making the investigation a top priority. The outcome could change how tour buses operate on city streets.
Calls to City Sightseeings seeking comment have not been returned.
