Bystander Intervention: I was walking south on Broadway…

I was walking south on Broadway in front of Fairway and witnessed a white woman @ mid-sixties raise her arm over her head and strike a smaller Asian woman on her left shoulder – hard. The victim stopped and grabbed her shoulder and was confused about what had happened. I told her that I saw the woman deliberately hit her and she then became scared. I ran after the perp trying to get a decent photo but lost her at the intersection. I can’t say with certainty that this incident was racial, but it happened at the height of Trump’s “China virus” agitating. I doubled back to Fairway but couldn’t find the victim.
I was furious and wish I had been more effective. Next time. >:-(