A quote from further down the article:
The police then announced to the protesters from a vehicle with a megaphone that they were an illegal assembly and would be detained and fined if they didn’t leave. Around 10 a.m., the men in T-shirts rushed the crowd and dispersed them. Zhang said she saw women dragged down the stairs of the bank entrance. Zhang herself was hit, and said she asked the officer, “Why did you hit me?” According to her, he responded: “What’s wrong with beating you?”
Yang said he was hit by two security officers including one who had fallen off the stairs and mistakenly thought in the chaos that Yang had hit or pushed him.
Sounds about right.