After 24 weeks of unrest, Monday (November 11) showed that Hong Kong's protests have not lost their capacity for shocking violence.
One protester left in a critical condition after being shot at close range, amid a dramatic escalation in violence.
Hong Kong police claimed the officer was acting in self defense and that a protester had been trying to snatch his gun.
A friend, who visited the wounded man in hospital, said he hadn't done anything and "they just shot him".
The 21-year-old fell just a a couple of meters from a makeshift memorial to a student who died in a fall from a car park last week as protesters were being dispersed by police.
That's poured more oil on Hong Kong's almost daily protests and the scenes on Monday are an escalation.
It's rare for tear gas to be fired in working hours in places like the central business district, on streets lined with bank headquarters and top-brand shops.
Banks were one target of the protesters' anger on Monday.
Videos circulated online showed a man dousing petrol on another and setting him on fire.
Police condemned the incident and said the victim had been in a disagreement with protesters.
Hong Kong's Hospital Authority said a man had been admitted with severe burns.
In one of her most defiant addresses to date, and just hours after the police shooting, Hong Kong's leader Carrie Lam said the violent acts of protesters should be condemned by the whole of society.
(SOUNDBITE) (Cantonese) HONG KONG CHIEF EXECUTIVE CARRIE LAM SAYING: "The action of rioters has far exceeded the call for democracy and are now people's enemy." China, which protesters accuse of eroding Hong Kong's freedoms, was tight-lipped over the mayhem.
(SOUNDBITE) (Mandarin) CHINESE FOREIGN MINISTRY SPOKESMAN, GENG SHUANG, SAYING: "This is not a diplomatic affair.
I suggest you to Hong Kong and Macau Affairs Office for your question." China has a garrison of up to 12,000 troops in Hong Kong who have kept to barracks throughout the unrest, but it has vowed to crush any attempts at independence.
Police said more than 120 places were either vandalized or blocked by protesters on Monday.
Some 266 people have been arrested over the past week.