"The police say they're here to help but we were there to make the change and I feel like we didn’t get anywhere that night,"Ms Antonio said.

"We weren't doing anything wrong. We weren't trying to hurt them. But they were trying to hurt us and it was wrong,very wrong,for them to do that."

Earlier in the day,there was no sign of the trouble to come.

As the crowd gathered at Town Hall for the 3pm rally and marched down to Belmore Park,police stuck to the perimeter and protesters were vocal – shouting"all cops are bastards"and other jeers.

Superintendent Gavin Wood told theHerald as the march moved through Goulburn Street:"It really has been fantastic,it's been a great spirit and it's a perfect example of working hand in hand with the community."

At Belmore Park,a DJ played music and the crowd danced near a shrine to honour David Dungay Jr,an Indigenous man who died in custody in 2015.

Soon after 5pm the DJ announced the last song and told everyone to"get the f--k out of here",so as not to give the police any excuse for violence. By 5.30pm there were only a few stragglers remaining.

What happened next is contested.

Herald reporters – including this one – and photographers were there on the night. There were also at least 20 legal observers from Amnesty International and various community legal centres taking detailed notes with time-stamps.

NSW Police allege that at about 5.45pm,a small group of protesters gathered on Eddy Avenue near Pitt Street and refused to move on,despite requests from police.

Legal observer Cameron Caccamo,27,said an Aboriginal police liaison officer asked the protesters on Eddy Avenue to leave. Mr Caccamo said a protester with a megaphone said"we should respect Indigenous voices present"and asked everyone to start heading home.

Mr Caccamo said the message was filtering through the crowd and there was some movement as people prepared to leave. At that point,he said,the police started"forcefully pushing"everyone,forcing people to walk backwards because there was no time or space to turn around.

Police allege that the group surrounded a marked police car parked near the intersection of Eddy Avenue and Pitt Street and someone threw a brick. Photos supplied by police show a large dent in the front panel near the side mirrors on the passenger side. Members of the group allegedly banged and kicked the front and side panels as the car drove away.

Mr Caccamo said he did not see a brick or any other projectile thrown at the car,despite standing a few metres away and subsequently reviewing video footage. He said he heard a thud as the police car drove onto the road and he thought at the time it was the car side-swiping the metal fence. He said some protesters followed the police car for a short time but were not violent.

The protesters were pushed onto the footpath under the stone awnings on Eddy Avenue,up the pedestrian mall and through the ticket gates into Central station. The police allege that as they moved the group into Central,the protesters threw items,including a large drink can that struck an officer in the face. There is a video of at least one altercation between protesters and police on the footpath at Eddy Avenue but it is understood this incident did not result in arrest.

Stella,23,a volunteer marshall who asked for her surname to be withheld,said:"The speed of[the police] line was going too fast for people to get through. I felt incredibly crushed and there were people who ended up on the floor,there was a lot of falling over and people just trying to say to the police,'slow down,slow down'."

Police acknowledge they funnelled protesters into Central Station with the aim of getting them to go home. The protesters say they were never given clear directions.

Beyond the ticket gates is the station concourse,an area with multiple columns and a lift well between the wall and the platforms that could have made it difficult for people in the thick of the crowd to leave. However,the crowd thinned out over time until only 40-60 protesters,mostly young people,remained.

Social media posts describe the protesters as being"corralled into a confined space". However,Assistant Commissioner Michael Willing rejected this,telling ABC Radio on Friday morning the aim was always to get protesters to disperse.

"They were asked to move up into Central Station and all they had to do was turn around and get on the platform and go home,"Assistant Commissioner Willing said.

Inside the station,police say individuals continued to spit,kick and punch officers in the police line. There was one arrest at about 6.20pm,with police alleging a 21-year-old man from Mount Druitt became aggressive and threw a water bottle at a police officer and another item at a second officer,hitting him in the chest.

The man is facing four charges,including offensive behaviour,resisting arrest and two counts of assaulting an officer in execution of duty and is due to appear in court on August 27.

The crowd behind the ticket gates was mixed race and mostly young. Legal observer Jarrod Diamond estimated that at least two-thirds were under the age of 25 and half were visibly under 18.

The police used capsicum spray on the crowd between 6.45pm and 7pm. Police say this was to quell the violence of the crowd.

However,Mr Diamond and other legal observers who witnessed the event insist the crowd was rowdy but not violent. Some accounts say that when the police stepped back,the crowd stepped forward and this might have been misconstrued. Ms Antonio,who was near the front,describes being pushed forward by the crowd.

Shortly before the capsicum spray,a young white woman called Jane Margaret hobbled forward on crutches to speak to police. She said later she had been at the protest march and was on her way home when she came across the trouble at Central Station and thought she might be able to calm the situation. She recounts in an Instagram video recorded from her hospital bed that instead,police sprayed her"point blank"along with other protesters.

Mr Diamond saw an arm holding a large orange container with a spray nozzle suddenly thrust out from the row of police and start spraying people. He also saw a second officer pull out a handheld canister –"about the size of a can of deodorant"– and spray people.

Police say five people were treated at the scene and observers say many others were given first aid by street medics and bystanders. A number of the spray victims were minors,including Ms Antonio and a boy aged 14,and a lawyer is considering helping them mount legal action against police.

The crowd was incensed by the police use of pepper spray and started banging on the metal ticket gates chanting"black lives matter". A woman screamed that it was meant to be a peaceful protest and the police had made it violent.

Soon after 7pm a senior police officer with a megaphone gave a formal move-on order,telling everyone to leave the area or they would face arrest. This time everyone listened.