HONG KONG -- A spokesman for the government of Hong Kong Special Administrative Region expressed outrage on Thursday at the violence of rioters that left a senior worker critically injured.

According to a statement from the HKSAR government, "an outsourced worker of the Food and Environment Hygiene Department, who is a senior, was suspected to be hit in his head by hard objects hurled by masked rioters during his lunch break yesterday (Nov 13)."

The worker was described as suffering "serious injury and is in critical condition."

A spokesman for the HKSAR government said that he was "saddened by the incident" and said the government "is in contact with family members of the worker through the service contractor and will provide all appropriate assistance to them."

Meanwhile, he expressed "outrage over the malicious acts of the rioters and emphasises that police will follow up the case thoroughly to bring offenders to justice."

"Masked rioters conducted extremely dangerous and violent acts in various districts three days in a row, where they wantonly assaulted other members of the public," he said. "The acts are outrageous. Police will resolutely take law enforcement actions to restore public order. The HKSAR government appeals to members of the public to stay calm and rational as well as to stay away from violence to safeguard personal safety."

Video footage circulating online showed that the man, in a checked shirt and a dark coat, was standing facing some black-clad rioters who were hurling what seemed to be bricks, before he was hit and fell down.

This is not the first time ordinary residents in Hong Kong being assaulted in the unrest.

On Monday, a 57-year-old man was beaten up by rioters on a footbridge in the Ma On Shan area because of different political view, and he was poured with suspected flammable liquid and set on fire by a rioter.

The man was still in critical condition at hospital with second-degree burns on 40 percent of his body, the Hong Kong police said on Wednesday.