The takeover came as thousands of people gathered in nearby Tamar Park for a rally to mark the start of the 2014 protests.
Bricks were being ripped up from a pavement to be ferried in metal drums to those protesters closest to a group of riot police by the government complex.
The bricks were hurled at the riot officers, who were initially some distance away behind water barriers.
A helicopter circled above the area at one point, with some people shining laser pointers at it. There was also an intense light show going on outside the People’s Liberation Army building.
At around 8pm, a police water cannon vehicle was brought close to the protesters from inside the government complex, with sudden cries for umbrellas to be rushed to those at the frontline.
Police officers also fired a pepper spray based solution at some of the crowd.
Soon after raising the red and black warning flags, officers started firing the water cannon as well as tear gas in a bid to disperse the demonstrators.
The crowd moved back but did not disperse.
Traffic on both sides of the road had been very quickly brought to a standstill when the blockade began shortly before 7.30pm.
One motorist caught up the drama told RTHK he wasn’t bothered about the inconvenience caused by the action and what the protesters were doing was more important than his journey.
But a taxi driver said he was too afraid to speak to the press, in case the protesters beat him up.
Even before the rally had got underway shortly after 7pm, riot police had fired pepper spray at a group of protesters who they said had been shining laser pointers at them outside the entrance of the Central Government Complex.
Last updated: 2019-09-28 HKT 20:56