Here are some emails I got from the PA group of the National Incident Network, they send emails about emergency situations.
10:42 am York_County: Disturbance, 155.475 York City - group forming in street at Market & Duke, 1 blk from white supremacist rally at library. PSP helo observing, PSP command post coordinating on national.

11:04 am York_County: Disturbance, 155.475 York City - Update - group of 50 at Market & Duke "masking up" - other groups forming in other areas of downtown

11:07 am York_County: Disturbance, 155.475 York City - Update - PSP mounted officers moving into area to break up crowd

12:57 pm York_County: Disturbance, 155.475 York City - Update - WS meeting is underway in library - groups still posturing in various surrounding areas - PD anticipating arrests in area of Queen & King Sts

1:46 pm York_County: Disturbance, 155.475 York City - Update - Two groups now actively fighting in Mason Alley - req more officers - officers & mounted officers en route

1:51 pm York_County: Disturbance, 155.475 York City - Update - Mounted units moving crowds - arrests made - most activity near King & Queen Sts