HONG KONG, Dec. 2 -- The Hong Kong police on Monday warned against the repeated occurrence of so-called "lynching" by rioters against other people, and pledged to investigate the cases with utmost efforts.

Chief Superintendent Kwok Ka-chuen of Police Public Relations Branch told a press briefing on Monday that the police were deeply alarmed by cases of rioters taking the law into their own hands and brutally beating up people with different political views.

In recent days, at least two cases of lynching happened in the Mong Kok area in Kowloon.

In the small hours on Monday, a man was attacked by a group of rioters as he was taking photos of them. The rioters also attempted to steal his cell phone.

In another shocking case one day earlier, a middle-aged man was struck in the head by a rioter with a manhole cover as he volunteered to remove barricades set up by the rioters. The attack could have been a murderous act, Kwok said.

What is more horrifying is that after the attack some netizens hurled insults and mocked the victim online, Kwok pointed out, warning that if people continue to condone violence like this, the community may see a decline in law-abiding consciousness and an increase of other violent crimes.

The police took all the cases that involve lynching very seriously and would investigate into them with utmost efforts, Kwok said.

The police have made arrests for some of the lynching cases, including the assault on a journalist from the Chinese mainland at the Hong Kong International Airport in August, the attack against a taxi driver in Sham Shui Po in October, and the torching of a man near the Ma On Shan metro station in November.

"I'm positive that most people in the society are tired of the rioting that has crippled Hong Kong over the past six months. No political slogan can justify crimes like arson, criminal damage and assault," Kwok said.

"The ongoing unrest has taken a heavy toll on the society. If we do not make a clear break with all the radicals, everyone will be a victim. We should stop letting violence take us as hostage," he added.