Chinese troops left their Hong Kong barracks on Saturday for a rare public appearance to help clean up the streets after further anti-government protests.
Dressed in shorts and T-shirts - and with Hong Kong's riot police keeping a close watch nearby - the People's Liberation Army (PLA) carried brooms instead of rifles and picked up paving stones, rocks and other debris left by demonstrators.
They have been seen on the streets only once since the former British colony was handed back to China in 1997 - to help clean up after a typhoon in 2018.
The Hong Kong government's failure to end more than five months of often violent protests has fuelled speculation that Beijing could deploy its troops.
China, which has up to 12,000 soldiers in Hong Kong, previously said it could do so, in an effort to stop the protests, although technically a request would have to come from Hong Kong's government.
And such action would spark international criticism and bring back memories of the army's fatal crackdown on pro-democracy protesters in Tiananmen Square in 1989.
But the move by China's PLA to help with the clean-up in Hong Kong was initiated as a "voluntary community activity" by the military, according to a city spokesman.
Saturday's move follows some of the worst violence seen this year, after a police operation against protesters at the Chinese University of Hong Kong on Tuesday.
The authorities have since largely stayed away from at least five university campuses that had been barricaded by thousands of students and activists who stockpiled petrol bombs, catapults, bows and arrows and other weapons.
Many protesters appeared to have left the campuses by late Saturday, although some remained behind to man barricades.
Sky News' Asia correspondent, Tom Cheshire, visited Polytechnic University, where he said a few hundred protesters had blocked roads and turned the scene into a "fort".
He said: "The police showed up opposite the front of Polytechnic University and they started firing tear gas. A lot of tear gas everywhere. The protesters began retreating inside. It was very confused, very chaotic.
"I got a glancing blow from a tear gas canister as we were retreating inside."
He added: "Now, everyone's here waiting for an attack to come, wondering whether the police are just trying to tire people out because what they've been doing all night is switching the focal point of attack.
"It's coming up to 1.15am here and I think the police are very happy to wait this out and see if people will leave.
"We're going to wait it out and see but, you know, they've been preparing for a siege for the last four days. The siege has now come - how it holds up we'll wait and see."
On Thursday, a 70-year-old street cleaner died after being hit on the head by a brick that police said had been thrown by rioters.
:: Listen to the Daily podcast on Apple Podcasts , Google Podcasts , Spotify , Spreaker
And on Monday, police blamed a rioter for dousing a man in petrol and setting him on fire - the victim remains in a critical condition.
On the same day, police shot a protester in the stomach - the person is said to be in a stable condition.