Eight MTR lines were hit hard, and the railway operator arranged for 15 shuttle buses to ferry stranded commuters.
Tempers flared, and at Fortress Hill station, a man became distressed, yelling that his pregnant wife was about to go into labour and angrily waving aside protesters who offered to help.
Video clips showed a black van ramming through barricades set up by protesters outside the Cross-Harbour Tunnel’s Hung Hom exit, and a taxi mowing down picketers trying to block Harcourt Road in Admiralty.
A man who drove through a barricade was earlier stopped by an angry crowd at Healthy Street West, some of whom punched him and shattered his windscreen as he got out and argued. A protester said the driver almost hit people with the vehicle.
Shops and businesses across the city closed early, and workers were given the rest of the day off to avoid any chaos heading their way.
Airport services were hit hard as well, with some 250 flights cancelled as air traffic controllers called in sick and airline staff joined the strike.
Protesters first took to the streets for what they billed as peaceful rallies in seven locations during the day. But before long it was apparent many were out to target police officers and their stations.
They vandalised multiple stations, throwing bricks, eggs and other projectiles at the windows and building fronts, spray-painted obscene graffiti on the walls, and yelled insults at officers who mostly remained barricaded inside.
The mobs used wooden crates, branches and rubbish bins to start fires at the gates of several police stations. At the Sha Tin police base, the fire became large enough to force officers from higher floors in the building to spray water on the flames.
For the first time in two months of mass protests which were triggered by the extradition bill, police fired tear gas early in the day, their patience running low under an endless barrage of attacks and abuse.
At the first of daily press briefings that police will hold from now on, it was revealed that they had fired 1,000 rounds of tear gas since the first clashes erupted on June 9 and arrested 502 people in total.
The protesters played cat-and-mouse with police, retreating with each firing of tear gas and advancing again, the aim being to draw police out at multiple locations simultaneously to frustrate and wear them down.
Countless rounds of tear gas were fired in the business district of Admiralty and the tourist hub of Tsim Sha Tsui, as well as in the residential neighbourhoods in Wong Tai Sin and Tai Po, which were turned into war zones.
Tear gas was also used outside Tin Shui Wai Police Station, where an angry crowd accused police of sexual violence after a young woman’s underwear was exposed while she was taken away by several officers on Monday morning.
Senior Superintendent Yolanda Yu Hoi-kwan insisted officers had not behaved inappropriately, and blamed the woman for putting up a fight and resisting arrest.
At the press conference with Lam, Financial Secretary Paul Chan Mo-po appealed for an end to the protests, warning the economy was in trouble because of both the ongoing US-China trade war and internal instability.
Hong Kong stocks saw their longest declining stretch in more than two decades, with the Hang Seng Index dropping 2.9 per cent to 26,151 points.
Asked if she, or any member of her cabinet, would take responsibility for the social unrest and step down, Lam insisted she would not resign, especially when Hong Kong’s future was at stake.
“When the well-being of 7 million people is facing huge challenges, this is no longer about my personal honour. My colleagues and I have the responsibility to stand fast to our positions,” she said.