A Sweet 16 celebration in Sydney’s southern suburb of Kirrawee took an unexpected turn when around 500 uninvited teenagers showed up.

The birthday gathering on Bounty Avenue quickly descended into chaos as the night unfolded.

Footage that emerged on social media captured a tense standoff between law enforcement and a portion of the young crowd, which had become unruly.

One 16-year-old boy was taken into custody after allegedly hurling a full can of alcohol at officers.

Police, justifying their response, noted that “OC spray was deployed when bottles were thrown at police,” adding that the boy “resisted officers” during the arrest.

He was among three teenagers who were apprehended that evening.

All of them were later released without charge.

Neighbours said they were left shaken by what unfolded and many young children watched the chaos unfold on their doorsteps.

“There were a few people climbing over their neighbours fence here to get in and out of the party,” neighbour Aedan Byrne told 9News.

It took police, an overhead helicopter and the riot squad more than an hour to disperse the crowd.

NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.