San Francisco, California, was an early adopter of mandatory preventative measures to curb the spread of the novel coronavirus COVID-19.
One mandate called for the wearing of masks on all public transportation in the city by staff and by passengers.
According to Newser, three young men without masks boarded a public bus Wednesday afternoon.
After repeatedly asking them to don face coverings, the driver pulled over to escort the men off the bus.
Police say one of the young men pulled out a wooden bat and hit the driver several times. The men fled and haven't been arrested.
The driver was left with injuries that were not life-threatening and is recovering.