This is a great example of protest art as propaganda.

This piece actually refers to a specific incident where the protestors attacked uncooperative bystanders (presumably fellow HK'ers) on a train at Prince Edward Station, one of whom used a hammer to defend himself:

https://www.youtube.com/watch?v=7IpfKRRbiEQ

Later the police were called by the subway authorities, and went ahead to arrest the now cowed protestors:

https://www.youtube.com/watch?v=c-wKmycZ_DA

The news only reported on the second video. You can also see how "Resist Girl" manages to turn reality into a completely distorted narrative.