Three young men remain in hospital under police guard after a violent brawl outside a kebab shop ended in a triple stabbing.

Security cameras captured the bloody confrontation in Canterbury, in Sydney’s southwest, which police say was no random attack.

WATCH THE VIDEO ABOVE: Three stabbed in Canterbury kebab shop brawl

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The scuffle lasted just seconds, but between the flying fists, all three men involved suffered serious stab wounds.

“A 23-year-old man was at that fast food outlet and an 18-year-old man and a 24-year-old man, who are related to each other, attended that location and an altercation took place,” Superintendent Christine McDonald said.

The footage shows it was two against one before a witness stepped in to stop the violence.

Breaking up the fight, a relative of the two brothers involved claims they were the victims.

“This person just keeps bullying them, kicking on them, and he was pulling for the back of him and I think he was trying to pull out a knife,” he told 7NEWS exclusively. “And I think the boys, they got scared and they jumped on him.

“And it was just a simple ‘come and get a feed’ and this is what happened ... Very bad violence, it shouldn’t have happened.”

One knife was seized from the scene, but investigators believe there was a second weapon.

“We are currently making inquiries to locate and recover that weapon,” McDonald said.

Police were only alerted to the fight when the three men took themselves to Canterbury Hospital at separate times just after midnight.

“We are yet to speak to them in terms of interviewing them in relation to their involvement,” McDonald said.

All three men are in a stable condition following surgery on Monday.