(Bloomberg) -- Even before most of Hong Kong got to work Monday, protesters already had a fresh grievance against the police.

A traffic cop seeking to break up a rush-hour roadblock grabbed a masked protester in a headlock and shot another in the abdomen at close range. The demonstrator collapsed on the crosswalk as blood pooled under him, prompting speculation that he could be the first to die from police gunfire after five months of unrest. He is in critical condition.

The incident -- caught on video and widely circulated on social media -- added new fuel to criticism of police tactics already raging after a student died Friday from injuries suffered near a clash between cops and protesters. Moments later, another police officer was filmed repeatedly driving a motorcycle through a group of retreating protesters, striking several.

Activists attempted to use the shooting to rally support for more protests on Tuesday, circulating flyers on social media featuring an image of a revolver and calling on people to disrupt traffic during the morning commute. The University of Hong Kong canceled all classes on Tuesday. Hong Kong Professional Teachers’ Union urged a suspension of all classes at schools and kindergartens, according to a statement on its Facebook page.

Monday’s chaos showed the strains facing Hong Kong’s police, which the China-appointed government has relied on to suppress increasingly violent protests aimed at securing greater democracy. The shooting led protesters to flood the city’s central business district at lunch time -- spurring fresh outrage at police when they fired volleys of tear gas into streets and luxury malls, sending office workers sprinting to safety and to wash out their eyes.

“People in Hong Kong are getting more and more angry that the violence from the police is increasing,” said Tommy, 52, an accountant in Hong Kong who was with hundreds gathered in Central on Monday. “They just beat on protesters like terrorists. The most important solution is to have an independent investigation. But our government just doesn’t listen.”

Although police said they suspended the motorcycle officer pending an investigation, they defended the officer who discharged his weapon, saying he feared for his safety. Police have repeatedly reaffirmed their commitment to restraint, despite criticism from the United Nations, U.S. and U.K. lawmakers, and Amnesty International, which accused the force of torturing detained protesters. Police have denied that claim.

The shooting Monday was the third time a protester has been shot in the past two weeks, although all the victims have survived. The student who died Friday had fallen earlier in the week from a parking garage deck near a clash between protesters and police, making him the first such fatality.

Protesters have seized on police tactics to justify their own escalations in a city once known for its non-violent demonstrations. Hard-core activists now show up at protests wearing gas masks and body armor and hurl petrol bombs at police lines.

On Monday, a man was set on fire while arguing with one group in the northeastern area of Ma On Shan. He is also in critical condition.

“The level of violence used by the rioters has escalated significantly throughout these five months,” senior superintendent Kong Wing-cheung told a news briefing Monday. “I do not agree that our officers are out of control with their use of force, but of course we are under great pressure and our officers also encounter difficult times during our operations.”

Worn out by months of protests and trying to contain rallies that often pop up out of nowhere, the police find themselves outnumbered and surrounded. That’s what happened to the traffic officer who opened fire Monday. While he fired three shots, only one hit a protester.

“One of the most dangerous things any police officer can do is move away independently,” said Clifford Stott, a professor at Keele University in the U.K., who was one of the experts on an international panel appointed to advise Hong Kong’s Independent Police Complaints Council on the protests. “It’s highly stressful, they’re highly vulnerable, and in that context we’re likely to see extremely high levels of use of force.”

Numerous police officers have been injured since more than one million people flooded Hong Kong’s streets in June for what started out as a largely peaceful movement against legislation that would’ve allowed extraditions to mainland China. Officers have accused protesters of splashing them with noxious fluids and exposing them and their families to threats by circulating their personal information online.

Meanwhile, Chief Executive Carrie Lam has vowed not to give into violence and meet the protesters’ demands, including calls for direct leadership elections. The Chinese government last week reaffirmed its support for Lam, seemingly dashing any prospects for political change that could ease tensions between protesters and police.

“You can imagine that if you work constant overtime, you need to be cautious communicating with your friends, you can imagine the immense pressure,“ said Lawrence Ka-ki Ho, an assistant professor at the Education University of Hong Kong who studies policing and public order management.

Stott said the “unprecedented” scale and violence of the city’s protests make Monday’s incidents “perhaps unsurprising.” However, he said firing tear gas in the financial district at lunch time was rarely a good idea.

“We know from decades of research that those forms of policing tactics escalate disorder,” he said, stressing he wasn’t speaking in his capacity as an adviser to the IPCC. “The question for Hong Kong is: How does one deescalate the situation?”

--With assistance from Blake Schmidt, Natalie Lung and Erin Roman.

To contact the reporter on this story: Iain Marlow in Hong Kong at imarlow1@bloomberg.net

To contact the editors responsible for this story: Brendan Scott at bscott66@bloomberg.net, Colin Keatinge, Caroline Alexander

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