Two teenagers have been hospitalised after an stabbing at a family function in Sydney, after a group of boys crashed the event.

A group of five males crashed a family function at The Sapphire, on Station Road in Auburn, at about 10.15pm last night.

The group assaulted a 17-year-old inside the function centre before one of them stabbed him in the leg.

The 17-year-old was treated by paramedics before being taken to Westmead hospital in a stable condition.

Shortly after, a second boy, aged 18, showed up at the same hospital with stab wounds to his lower body, including on his leg.

Police believe he was also at the family function.

There is now a search underway for the five males, who police believe are known to the two victims.

Anyone with information about the alleged attack is urged to contact Crime Stoppers on 1800 333 000.