Hospital communications director Mary Anne Gill said the woman in question was a health professional who, while not employed by the hospital, was visiting in a professional capacity.
"Our hearts go out to her. It's really awful for this to have happened when she was just going about her work,'' she said.
"It was busy in the emergency department so for him to try this in broad daylight is pretty awful.''
Ms Gills said the hospital's security procedures had worked well and the reaction from staff couldn't have been quicker.
"A member of the public contacted our security people and within 45 seconds of that first call the security guards were over in the carpark and were on the lookout for this particular person,'' she said.
Police said the woman was badly shaken but not hurt.
The alleged attacker, who was found at an address in Deanwell, was being interviewed by police.
Mr Smith said the victim did everything right once she noticed she was under threat.
"She screamed to draw attention to her predicament and members of the public came to her assistance. If anyone finds themselves in a threatening situation like this, police advise you to make as much noise as possible to draw attention to your plight and possibly scare the offender away.''
