RIOT cops in Hong Kong have deployed a new "sonic weapon" to make protesters throw up as students fear a fresh massacre.
Police fired live rounds today as around 600 activists remained trapped in a university on the second day of a siege.
Cops said the rounds were fired after a group of protesters stationed at the Hong Kong Polytechnic University (PolyU) used homemade fire bombs to attack an ambulance transporting a 20-year-old woman under arrest.
Officers used what they described as a "long-range acoustic device" from an armoured lorry.
The high-pitched siren was a sonic weapon intended to cause nausea and disorientation, protesters claimed.
ESCALATING VIOLENCE
Protesters who voluntarily occupied the campus now want to leave - but claim police won't allow them to unless they give themselves up.
Police vehicles have fired volleys of tear gas and plumes of water, some of it dyed blue to stain the protesters' clothes - while activists retaliated with Molotov cocktails, bows and arrows and eggs filled with paint.
Demonstrators armed with bows and arrows last week launched flaming bows and javelins at cops as China threatened to send in troops to deal with the escalating violence.
A group of a hundred activists who tried to leave on Sunday were met with tear gas and rubber bullets.
This ongoing conflict has recalled the Tiananmen Square atrocity of 1989, when China's People's Liberation Army opened fire on pro-democracy protesters, killing thousands.
China has a garrison of up to 12,000 troops in Hong Kong.
They have kept to barracks since 1997 but Beijing has said that it will crush any attempt at independence, one of the demands being made by a small minority of protesters.
The police have formally branded the protest a riot - a crime carrying a jail term of up to ten years.
Some 13 people, aged between 22 and 57, were injured on Sunday. One is in a serious condition.
Sobbing parents have been seen begging police to take their children home but in vain, while other activists are determined to stay put.
“Before I wanted to surrender, but now I’ve changed my mind,” one 16-year old boy was quoted saying.
“I don’t want to stay here any longer but I don’t want to go to prison."
Officers have said protesters can leave, but only if they drop their weapons and remove their gas masks.
However, pro-democracy lawmaker Ted Hui - who is on the campus - said the bridge had "been sealed off", and it was not possible to leave this way.
The university is the last of four campuses that were occupied by protesters last week.
Protests have gripped Hong Kong for the past six months, sparked by plans to extradite criminal suspects to mainland China and Taiwan.
These plans have been dropped, but the protests have now expanded into a wider protest movement against police brutality and China's perceived control over the region.
Why are people protesting in Hong Kong?
The protests in Hong Kong began in June, over a proposed law.
The new rule would have allowed criminal suspects to be extradited to mainland China.
Activists saw the bill as another sign of an erosion in Hong Kong's autonomy and civic freedoms.
China had promised that Hong Kong would be maintained for 50 years under a "one nation, two systems" principle.
This pledge was made when the former British colony was returned to Chinese control in 1997.
Hong Kong leader Carrie Lam eventually withdrew the extradition bill.
She says protesters are being 'selfish'.
The US has condemned "unjustified use of deadly force".
It's urged demonstrators and police to calm down, and de-escalate the situation.
But speaking from Beijing, Chinese Foreign Ministry spokesman Geng Shuang urged Britain and America not to intrude.
China has a garrison of up to 12,000 troops in Hong Kong.
While they've been kept to barracks since 1997, China has threatened it will crush any attempts at independence - a demand for a minority of protesters.
Those demonstrating have called upon Hong Kong's politicians to stop labelling them as rioters.
Plus they want criminal cases to be dropped against activists.
Britain remains "seriously concerned" by escalating violence in Hong Kong and urges the authorities to agree "to a path to resolve the situation", a spokesman for Prime Minister Boris Johnson said today.
"We remain seriously concerned by the situation in Hong Kong and the escalation of violence between protesters and police. We continue to urge for calm and restraint on all sides and support the right to peaceful protest," the spokesman said.
"We believe political dialogue is the only way forward and we want to see the Hong Kong authorities agree to a path to resolve the situation," he said, adding Johnson had no plans as yet to make calls to the authorities.
Police have said Hong Kong was on the "brink of total breakdown".
On Tuesday accused protesters of committing "insane" acts, throwing trash, bicycles and other debris on to metro tracks and overhead power lines.
Senior Superintendent Kong Wing-cheung told a briefing: "Our society has been pushed to the brink of a total breakdown."
The total number of those arrested by police since the action kicked off in June has risen to about 3,560.