The San Francisco Police Department gave the city’s Board of Supervisors an earful at a Monday hearing about downtown traffic and pointed the finger for traffic violations squarely at so-called transit network companies (TNCs) like Lyft and Uber.

At a hearing in front of the city’s Land Use and Transportation Committee, Robert O’Sullivan, the department’s commander of municipal transportation, presented a dramatic graphic to city lawmakers breaking down traffic violations during a three month period.

According to Cmdr. O’Sullivan, on a dozen targeted days between April 1 and June 30 of this year, SFPD recorded 2,656 transit violations in SoMa, FiDi, and parts of the Mission, of which 1,723 occurred on account of TNC drivers.

That would make companies like Lyft and Uber the genesis of more than 64 percent of traffic crimes in those neighborhoods.

Note that O’Sullivan says SFPD recorded cars bearing stickers identifying them as TNC drivers; it’s not clear how many violations were committed on the job versus on drivers’ own time.

The overwhelming majority of problems stemmed from drivers straying into transit-only lanes. Of 1,715 such violations, 1,144 were TNCs. This one error accounts for more than two-thirds of TNC-related problems.

Perhaps notable is the fact that taxis bearing city-issued medallions may use these lanes, but Lyft and Uber drivers cannot.

Undefined “other violations” were the next most common error, with TNCs behind 306 out of 567, with the next most common problem being bike lane obstructions, of which TNC drivers committed 183 out of 239.

“This seems like a class-action problem,” said Supervisor Aaron Peskin. “We should take this to the state attorney general.”

Since O’Sullivan specifically instructed officers to record TNC-related problems during this period, it’s not clear if these results are typical of other times or reflect what’s happening to other neighborhoods.

A separate presentation at the same hearing claimed that San Francisco sees 170,000 ride-hailing trips during a typical weekday. Spokespersons for Uber and for Lyft were not immediately available for comment.

[Update: Lyft spokesperson Chelsea Harrison says simply, “We are supportive of holistic efforts to address congestion and have been in conversations with city officials for months to engage collaboratively on a pilot program to do just that.”

Uber public policy manager Alex Randolph says the company “shares concerns” about traffic, adding, “Every day in San Francisco, thousands of people use Uber in ways that complement rather than compete with public transit, bicycling and walking. Our aim is to continue contributing to a robust, multi-modal transportation network that works well for everyone.”]

This is not the first time that the city routed blame for traffic woes toward TNCs. Last December, for example, SFMTA suggested that the city should cap how many ride-hailing drivers it allows on the streets. Although at the time, a spokesperson for the Metropolitan Transportation Commission said that blaming these companies for downtown traffic is “probably giving them more credit than they deserve.”