Police are hunting a group of party crashers who showed up uninvited to a gathering and left three teenagers with stab wounds.

The chaos terrified local families who anxiously hid inside their homes as bedlam erupted outside on Zephyr Street, Austral, in Sydney’s southwest about midnight on Sunday.

WATCH THE VIDEO ABOVE: Gatecrashers stab three teens at Austral party

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Officers were called to break up a violent birthday brawl held in an Airbnb rental, with pepper spray used to keep roughly 70 partygoers, mostly in their late teens, under control.

“I’d probably describe it as a war, you know, because there were so many people involved,” a witness said.

Footage shows a 17-year-old boy was seen walking with a bloodied thigh, hiding behind a sign for several minutes before being escorted away. He was found in a car nearby and treated for stab wounds a short while later.

A 19-year-old was also stabbed in the chest, while another teen was left with lacerations to the hand.

“It was a chaotic scene,” Liverpool City PAC Detective Inspector Scott Houldin said. “Police protected themselves with a variety of use of force.”

Police seized a number of exhibits, including three knives.

The teens were attacked by unwelcome gatecrashers, with the birthday party spoiled after it was posted on social media.

“There’s not really anything that happens around these ways, you know,” one local said. “Pretty quiet street as well. Yeah, [it’s] just crazy,” a local resident said.

The mob crashed through neighbours’ fences to get away as police arrived.

The two stabbing victims spent the night in Liverpool Hospital and have been cooperating with police, who face the difficult task of identifying their attackers amongst the sea of partygoers.