It was then that a few members of the public who were "going about their business" saw the arrest unfolding.
"These members of the public pictured didn't bat an eyelid, they jumped in to assist this constable.
"They could clearly see she was overpowered and helped her till back-up arrived, which I assure you was seconds away.
"I don't know who you are, but you guys are superstars in my books," the poster wrote.
"So often we hear of people seeing something and doing nothing and unfortunately our officers are getting hurt all over the country just trying to do their jobs.
"Had these people not helped, how different could this situation have been?"
The police have asked anyone who knows who the Good Samaritans are to let them know.