Hong Kong police say a protester slashed the back of an officer’s neck with a “sharp-edged object” at the Kwun Tong MTR station on Sunday.

Video of the incident posted online showed the officer was walking with a group of colleagues when a man suddenly rushed up and stabbed him on the right side of his neck with what appears to be a box cutter, RTHK reported.

Another officer was seen subduing a man immediately after the incident.

In a statement, the force said the officer was conscious when he was taken to hospital, and two suspects were arrested at the scene.

Police say the officers were there to investigate a report of criminal damage.

It was just one of many incidents across the city from Tuen Mun to Tseung Kwan O on Sunday, as anti-government protesters once again attacked officers, government buildings and MTR stations, as well as shops, banks, and offices of people and companies viewed as being close to Beijing.

Police say protesters assaulted one officer by kicking him in the head. It said “rioters” in Shatin threw petrol bombs, setting a police vehicle on fire.

In Tseung Kwan O district, protesters attacked an officer in Hong Kong on Sunday evening, leaving the man with a bleeding head injury.

Suspecting the man was an undercover police officer, a crowd of masked demonstrators had confronted him on Tong Chun Street.

At least three male protesters beat and kicked him. One of them was seen holding some kind of tool, RTHK reported, which may have been used to assault the officer.

Afterward, a volunteer first aid worker attempted to treat his injuries, as he bled from the face and head.

Protesters then found an extendable baton, which are often used by undercover police, in his backpack. Someone then appeared to take the baton and throw it into a drain.

Riot police then descended on the scene and pushed journalists back.

One officer attempted to lower himself into the drain in an apparent attempt to retrieve the baton but failed to reach it.

The police force later said in a statement that two plainclothes officers were assaulted by “mobs of rioters” at around 7.30 pm in Tseung Kwan O, causing head injuries to both.

“We were infuriated by rioters’ brutal assaults. The police will carry out thorough investigations against all violent acts,” the statement said.

Anti-government activists have condemned the police practice of undercover officers infiltrating groups of protesters, often accusing the police of trying to stir up trouble.

There have been a number of attacks on people suspected of being undercover police, with officers pulling out their guns and firing warning shots on at least two occasions.

The force said officers came under attack from protesters throwing bricks and other hard objects, and warned that further dispersal and arrest operations are forthcoming.

– with reporting by RTHK, Hong Kong Free Press and The New York Times