This is the shocking moment a Texas State University student was left with brain damage after being attacked allegedly by Pi Kappa Phi fraternity members.

Nikolas Panagiotopoulos, 22, claims he was set upon by at least half a dozen members of the Pi Kappa Phi fraternity's Eta Rho chapter in San Marcos on October 27.

Panagiotopoulos, who lives across the street from the frat house, claims he was walking by at about 2.30am when he was attacked.

He claims the frat members mistakenly believed he was a member of a different social group when they started heckling, taunting and harassing him.

The attack allegedly occurred when Panagiotopoulos tried to flee.

A mob can be seen fighting (pictured) in the street outside the Pi Kappa Phi fraternity house at Texas State University at the end of October this year. The victim of the attack, 22-year-old Texas State University student Nikolas Panagiotopoulos, is suing the fraternity for $1 million

Cellphone footage of the incident, which was filmed by a woman, captured Panagiotopoulos being tackled and then brutally beaten.

The woman filming could be heard yelling for the group to 'leave him alone' and that she would 'call the cops' if they didn't stop.

Panagiotopoulos claims the attack left him with a fractured skull and brain damage.

He filed a lawsuit last week against the fraternity seeking $1 million in damages.

The lawsuit names fraternity members Peter Piralla and Kevin Jimenez, as well as fraternity alumni Josue Jimenez, as being among those who allegedly attacked Panagiotopoulos.

The father of the chapter's then-vice president, Matthew Lawyer, said his son was inside the house when the incident occurred. He said he believed Panagiotopoulos was the one who started the confrontation.

Panagiotopoulos' attorney Jay Harvey told KVUE that Panagiotopoulos was minding his own business in the moments before he was beaten unconscious.

'Nik tries to run away,' Harvey said. 'This mob of these fraternity guys chase after him and continue to wail away on him, leaving him unconscious on the side of the street.'

Two months after the attack, Panagiotopoulos' attorney said the student is still recovering from trauma to his spine and skull and requires a wheelchair to get around.

Nikolas Panagiotopoulos (pictured), 22, and a friend allege they were set upon by at least half a dozen members of the Pi Kappa Phi fraternity as they walked past one of the buildings belonging to their Eta Rho chapter on the night of October 27 this year

The altercation allegedly started when frat members began to antagonize Panagiotopoulos from outside the building. Pictured is the altercation (both images)

Texas State University said that they suspended the fraternity 'immediately' after the attack in October. The Pi Kappa Phi house is pictured in October

The senior, who was unable to finish his university coursework after the attack, has spent months in hospital and was advised to skip Christmas with his family in New York due to his injuries, according to the lawsuit.

He suffered brain damage, fractures to the skull, psychological trauma and emotional distress after the attack, his attorney said.

'What's lost in all of this is that Nik lives right next door to the frat house, so he's constantly reminded of it,' Panagiotopoulos' other attorney, Sean McConnell, said.

'He lives right across the street. So he's constantly reminded of the frat and everything that happened to him that night.'

Panagiotopoulos is hoping to graduate in May 2020.

The $1 million lawsuit accuses the fraternity of failing to take responsibility for the unruliness of the mob outside the building.

His attorneys have started investigating the fraternity chapter, saying they should have known its members were aggressive.

They have also criticized the frat's history of 'encouraging' heavy drinking.

An undated file photo shows Texas State University. The lawsuit also accuses the fraternity of failin to diffuse the situation, failing to stop the aggression, and failing to monitor the members

The attorneys allege that the organization has a 'history of encouraging consumption and over-consumption of alcohol' and encourages 'rivalries with members of other fraternities and social clubs'.

'The attack was precipitated by a culture within the fraternity that encouraged drinking, bullying, and violence,' the attorney said in a statement.

Texas State University said that they suspended the fraternity 'immediately' after the attack in October.

The fraternity was later banned for four years after they were found to have been 'hazing' new initiates.

Pledges at the University of Texas reported being placed in a dark, claustrophobic room, and had to finish a 500-piece puzzle while strobe lights flashed and dance music blared through speakers.

At the time, the CEO of the fraternity, Mark E. Timmes, agreed with the university's decision and said: 'Hazing has no place in the fraternity and is contrary to our fraternal values.'

The organization declined to comment further on an ongoing investigation.