The head of a junior rugby league division, which saw players from two rival NSW teams in a violent all-in brawl, has said the guilty players could be banned from the competition for more than a decade.

Police are investigating after video emerged showing 17-year-old Gordon McRandal being thrown into a table by players from Riverstone, after McRandal’s team Cambridge Park had just won the grand final in the Under 17s Division Three clash in Sydney’s west.

Video of the all-in brawl, which occurred at Windsor Sports Ground 20 minutes after the grand final presentation, showed players rushing into the clash as parents screamed in the background.

Phil Cummings, the general manager of the Junior League, told 9NEWS there would be severe penalties for the players involved.

“As soon as the police investigation has concluded, we’ll be looking to suspend those players for about ten years plus from the junior league,” Mr Cummings said.

“It looks as though the two teams were leaving the ground, something’s happened, there was obviously a few words exchanged and then a bit of push and shove.

“Any person involved in that kind of behaviour will be dealt with harshly.”

The injured teen, who suffered a black eye and scratches, is expected to make a formal police complaint.

His father, who had tried to intervene, said his son had also sustained fractured ribs.

It is believed the player, known as “Gordy”, had also been sent off the field in the final moments of the game.

The brawl reportedly started after an argument between a couple of players.

A parent of a Riverstone player wrote on Facebook today that tensions had been simmering between the teams for some time.

“It’s been brewing all season. Every single game has turned into a disgrace,” Kelly Jurd wrote.