HONG KONG: At least 45 people were injured, with one person in critical condition, after a group of masked men attacked anti-government protesters and commuters at a Hong Kong train station on Sunday night (Jul 21), according to the city's hospital authorities.

The group, many wielding sticks and clad in white T-shirts, flooded into a Mass Transit Railway (MTR) station in the rural Yuen Long district, storming a train and attacking passengers, according to footage taken by commuters and opposition lawmaker Lam Cheuk-ting.

READ: Police took longer to get to Hong Kong train station attacks as manpower was 'stretched': Police Commissioner

Eyewitnesses said they appeared to target black-shirted passengers who had been at an anti-government march and the attack came after several thousand activists surrounded China's representative office in the city, later clashing with police.

Footage broadcast live on Facebook showed people screaming as the men beat multiple protesters and journalists in the station and inside trains, leaving pools of blood on the floor. 

One government worker, aged 22, described chaotic scenes as people ran in disarray off a train under attack, despite word that gangsters were assaulting people on the street as well.

"People started to run in all directions, just avoiding the gangsters," he said.

READ: Masked men assault protesters, commuters in Hong Kong MTR station

Critics rounded on the city's embattled police force, accusing officers of taking more than an hour to reach the station despite frantic calls from those under attack and then failing to arrest the armed men who stayed in the streets around the station into Monday morning.

Some men in white shirts were later filmed leaving the scene in cars with Chinese mainland number plates.

Lam, a pro-democracy lawmaker, was one of those wounded in the melee, sustaining lacerations to his face and arms. He criticised police for their response and accused "triad members" of being behind the attacks.

"Their very barbaric and violent acts have already completely violated the bottom line of Hong Kong's civilised society," he told reporters early on Monday.

"Is Hong Kong now allowing triads to do what they want, beating up people on the street with weapons?"

"TRIADS ARE BEATING UP HONG KONG PEOPLE"

Furious fellow pro-democracy lawmakers held a press conference on Monday where they accused the city's pro-Beijing leaders of turning a blind eye to the attacks.

"This is triad gangs beating up Hong Kong people," fumed Alvin Yeung. "Yet you pretend nothing had happened?"

The clashes have ratcheted up fears that the city's feared triad gangs are wading into the political conflict.

Yuen Long lies in the New Territories near the Chinese border where the criminal gangs and staunchly pro-Beijing rural committees remain influential.

Similar assaults by pro-government vigilantes against demonstrators during the 2014 "Umbrella Movement" protests were blamed on triads.

READ: Tear gas and rubber bullets fired as Hong Kong returns to chaos

As the mob rampage unfolded in Yuen Long, police were simultaneously battling hardcore democracy protesters in the middle of the city's commercial district.

Riot officers fired tear gas and rubber bullets at anti-government protesters, hours after China's office in the city was daubed with eggs and graffiti in a vivid rebuke to Beijing's rule.

Another 13 people were injured after the clashes on Hong Kong island, one seriously, the Hospital Authority said.

In a statement on Monday, police "strongly condemned" both the violent incidents in Yuen Long and Hong Kong island, and said they were investigating both cases. Police added no arrests had been made at the station or during a follow-up search of a nearby village.

Yau Nai-keung, Yuen Long assistant district police commander, told reporters that an initial police patrol had to wait for more reinforcements given a situation involving more than 100 people. 

He added police saw no weapons when they arrived although eyewitnesses said they saw groups of men in white with poles and bamboo staves at a nearby village.

"We can't say you have a problem because you are dressed in white and we have to arrest you. We will treat them fairly no matter which camp they are in," Yau said.

READ: What lies ahead for Hong Kong, a city on edge

Hong Kong has been plunged into its worst crisis in recent history by weeks of marches and sporadic violent confrontations between police and pockets of hardcore protesters.

The initial protests were lit by a now-suspended Bill that would have allowed extraditions to mainland China.

But they have since evolved into a wider movement calling for democratic reforms, universal suffrage and a halt to sliding freedoms in the semi-autonomous territory.

The city's parliament was trashed by protesters earlier this month, as Beijing's authority faces its most serious challenge since Hong Kong was handed back to China in 1997.