Protesters use water hose to defend themselves against marauding gang at Hong Kong station

Commuters used a water hose to fight back against masked thugs in white shirts who attacked them at a Hong Kong station on Sunday (July 21).

In the shocking clip filmed by a local citizen, first responders arrive at Yuen Long Station to rescue a young woman injured by thugs wielding batons.

The large gang of assailants attacked people who earlier had taken part in an anti-extradition bill protest in downtown Hong Kong in black T-shirts - as well as commuters caught up in the melee - at the station's ticket gates.

A man in a white T-shirt holds a board saying "Protect Yuen Long! Protect our home!"

In the video, one man with a stick rushes in and starts striking people near the ticket gate, including a woman in a yellow high-vis jacket who falls to the ground, felled by several blows.

A man can be heard saying in his native Cantonese: "You even hit a journalist! Are you mad?"

Another woman in a white dress also falls to the ground in the melee.

To protect themselves, people on the filmer's side of the ticket gate hold up umbrellas as projectiles are thrown in their direction and spray water from a hose and a fire extinguisher in the direction of the white-shirted mob.

The video comes to an abrupt end when the white-shirted mob appear to be about to rush the group of protesters and the filmer flees. The filmer escaped injury.

According to reports, the fight lasted for around two hours. Forty-five people were sent to hospital for their injuries.

Earlier in the day more than 100,000 had marched through Hong Kong demanding greater democracy.