SEMI-AUTOMATIC weapons, a silencer, disguises and a gunman who arrived at a casino to shoot a woman while he kept a taxi waiting outside.It could have been an episode of Underbelly but it was a real-life drama that unfolded at Pyrmont yesterday - one that proved a nightmare for police, stopped traffic and delayed the Prime Minister's visit to open the nearby headquarters of Fairfax Media.When the dust had settled and a suspect aged in his mid-20s was in custody, police revealed the man had arrived at Star City casino about 2pm and paid a taxi driver to wait for his return.He then caught a lift to the fifth floor and marched into the gym before allegedly shooting a female fitness instructor three times in the pelvis and stomach. The woman, aged in her 30s, remains in a stable condition in Royal Prince Alfred Hospital.A Fairfax staff member, who did not wish to be named, was in the gym when the shooting occurred."I'd just got out of the pool after swimming laps and had walked over to the water cooler for a drink when I heard this loud bang, and it scared the shit out of me," he said. "At first I thought it was a car backfiring and I turned and saw this guy with a gun."He said the man was standing about a metre from the gym's yoga instructor, named Holly."When I first saw him pointing the gun I thought it was a starter pistol and maybe he was joking, but then I saw her face and the look of horror."The witness said he then "freaked out" and ran into the change rooms until the man had fled. He said the gunman, who he had never seen before, looked angry when he walked into the gym just minutes before the first shots were fired."He looked a bit miserable-looking, just unhappy, he just had an unhappy aura."I heard one of the staff members say she heard Holly tell the man: 'It's not worth it'."The witness said the victim had been the gym's yoga instructor for between six months and a year."She was a really sweet girl, a typical yoga instructor - really mellow and placid. She was very athletic, had good posture, really tall, brown hair a really attractive girl."Police say the suspect did not return to the taxi, instead fleeing to a nearby office block on the corner of Pyrmont Street and Pyrmont Bridge Road.Office workers said the gunman entered their building via the basement car park, went up the fire stairs and locked himself in a toilet for the disabled.Police Inspector Brenton Lee said witnesses alerted police, who evacuated sections of the building and waited outside until the man emerged wearing a disguise.Shortly after he was arrested and handcuffed, three handguns, including an automatic pistol, lay on the street corner, as did a silencer, hinged knife, fake police identification and rubber mask."This was one of the most dangerous situations I have come across in my career," Inspector Lee said. "There were a number of firearms it is alleged that he was carrying at the time of his arrest as well as several ways to disguise himself. He appeared to be wearing false facial hair."Inspector Lee said the woman knew her alleged assailant.Hotel guests on level five were unaware of the drama. One family from New Zealand, on their first day in Australia, returned to their room about 3.15pm after shopping to be told by Fairfax of the shooting near their room."Boy, welcome to Australia," one male guest remarked.Chris Beghin, 31, an employee with the advertising firm Whybin/TBWA, located on the first floor of the office building the suspect fled to, said employees thought it was a joke when their chief executive emerged from his office to tell them a gunman was on the loose in their building."By the time we had evacuated to downstairs, police were coming in with body armour and I realised this was no joke," he said. "It is a tad concerning that the streets of Pyrmont seem to be populated by lots of guys with guns."