Hong Kong (CNN) Hong Kong's airport resumed operations Wednesday, just hours after thousands of anti-government protesters forcibly blocked access to the main terminal , temporarily paralyzing the transport hub for the second consecutive night.

Chinese government authorities strongly condemned the protesters on Wednesday, describing their actions as having "broken the bottom line of the law, morality and humanity."

"They committed serious violent crimes under public gaze, which is horrific and chilling. Their behaviors show extreme contempt for the rule of law," said Xu Luying, a spokeswoman for China's Hong Kong and Macao Affairs Office.

On Wednesday evening, police and protestors faced off in the residential Sham Shui Po area -- around 19 miles east of the airport.

A demonstration was taking place outside a police station when the skirmish started and tear gas was deployed.

Earlier this week, Chinese state media circulated video purporting to show an increased military presence in the city of Shenzhen on Hong Kong's border. There has so far been no indication that troops are set to be deployed.

The protest movement started in early June in opposition to an extradition bill, which critics fear could be used to target dissidents in Hong Kong for prosecution in mainland China. The bill has since been shelved , but the uproar stoked a wider civil unrest that shows no sign of abating.

Tuesday saw several flashpoints, as protesters overran airport security, using luggage carts to set up barricades in front of security checkpoints, while blocking passengers from accessing their flights.

Protesters at Hong Kong International Airport block the entrance to the security checkpoint on Tuesday, August 13.

With tensions high, protesters surrounded a man they claimed was a mainland Chinese police officer who had attempted to infiltrate the protests. Chinese authorities later identified the man as Mr. Xu, a Shenzhen resident who they said had traveled to Hong Kong airport to see off a friend.

Paramedics treated the man after he appeared to faint, but protesters would not let them evacuate. A tense, hours-long standoff ensued before police arrived and helped first responders get the man to the ambulance.

Riot police arrived shortly after, only to retreat. But a brief clash ensued with uniformed police, during which one protester was filmed attacking an officer from behind and grabbing his baton. The officer grabbed a gun from his holster in response, but did not fire it.

Police officer had his baton taken from him and was attacked with it. Drew his pistol and aimed at protesters. Astonished nobody killed here tonight. pic.twitter.com/Wox8yziDnz — Mike Bird (@Birdyword) August 13, 2019

Demonstrators also detained and tied a Chinese national to a luggage cart. The man was later identified as a reporter from Global Times, a Chinese state media tabloid, by the paper's editor-in-chief. Both he and Xu are still in the hospital, Chinese authorities said.

A Global Times reporter is zip-tied during the protest.

In a press conference Wednesday, Hong Kong police accused protesters of assaulting and imprisoning one man, and preventing medics from assisting him. Mak Chin-ho, assistant commissioner of police, told reporters that some protesters made "roadblocks and used laser pointers" to stop police meaning "it took a few hours to reach the injured man."

Mak said one police officer pulled out a gun in defense after "protesters pushed him to a corner to beat him up, and grabbed his pepper spray and baton."

Police warned that carrying out illegal activities at the airport could incur heavier penalties, including up to life imprisonment.

Airport operations resume

As airport operations began Wednesday, scars from Tuesday night's unrest were still visible as staff worked to remove stains from the floors and graffiti from the walls.

The airport announced that officials would start checking boarding passes and passports at the entrance of the departures hall from 2 p.m. (2 a.m. ET) on Wednesday.

Timothy Wu, corporate communications assistant manager at Hong Kong International Airport, told CNN that only the departures entrances would be monitored for now. Two of the entrances have been closed, and only two remained open.

More than 74 million passengers traveled to and from the airport last year. It handles 1,100 passenger and cargo flights each day, and serves about 200 destinations around the world.

Airport authorities announced Wednesday that they obtained an interim injunction allowing them to restrain people who are "unlawfully and willfully obstructing or interfering with the proper use of Hong Kong International Airport." The injunction will likely help airport authorities prevent a repeat of Tuesday.

Protesters seen at the arrivals hall of Hong Kong International Airport on Tuesday evening.

A city on edge as apologies issued

On Wednesday, protesters began issuing apologies for the disruption caused at the city's airport Tuesday night.

Numerous statements posted in a private messaging channel used by protesters expressed remorse and appealed for understanding. "We apologize for our behavior but we are just too scared," read one post. "Our police shot us, government betrayed us, social institutions failed us. Please help us."

Another message directly addressed different groups: "To all the reporters, ambulance staff, airport staff, and affected passengers, we again would like to express our deepest apology to all the inconvenience and disruptions."

The messages, which were issued anonymously, come as Tuesday's violence was given prominent coverage across mainland Chinese state media.

China has adopted a more strident tone in recent weeks focusing on violence and framing the protest movement as one of radical separatists being controlled by foreign "black hands." On Monday Chinese authorities said the situation in Hong Kong had "begun to show signs of terrorism."

But the protesters are by and large are young, angry and leaderless. They complain that the government has continued to ignore their five demands, which include calls for universal suffrage and investigations into alleged police brutality and misconduct.

Hong Kong leader Carrie Lam has repeatedly apologized for her government's botched handling of the extradition bill that sparked the protest and vowed to do a better job of listening. But she said the political issues will only be dealt with after law and order resumes.

"The Chief Executive's responsibility is to ensure that Hong Kong remains a safe and orderly and law-abiding city. That is my utmost responsibility," Lam said.

"After the violence has been stopped, and the chaotic situation that now we are seeing could subside -- I wouldn't say it will be eradicated totally -- I, as the Chief Executive, will be responsible to rebuild Hong Kong's economy, to engage as widely as possible, to listen as attentively as possible to my people's grievances and try to help Hong Kong to move on."