Police held a teenager at a gunpoint over a fake pistol after a costume party got out of hand. 

Officers were called to a home in Forestville on Sydney northern beaches about 8.30pm on Saturday night following reports uninvited teenagers had gatecrashed a house party.

It’s understood the host contacted police for assistance in removing the gatecrashers.

Police were allegedly confronted by 150 people – mostly teens – in the street when they arrived at the scene

The group were allegedly uncooperative and began to throw glass bottles at officers, prompting calls for specialist officers and police back-up to be deployed to the scene.

During the confrontation, police approached a 17-year-old male after they were alerted to a suspected firearm tucked inside his waistband.

‘The teen complied with their directions,’ a NSW Police spokesperson said.

‘Officers removed the item from his waistband, which was confirmed to be a toy pistol.’

It’s understood that the teen was an invited guest at the party. 

It’s not illegal to own a toy gun in NSW but it was not immediately apparent to police that the gun was not a real firearm.

Officers treat all guns as real until proven otherwise, a police spokesperson told Daily Mail Australia.

Footage of the incident obtained by the Manly Observer, shows the teenager with his hands behind his head and surrounded by armed police.

Police can be seen moving towards the boy with their weapons raised.

‘What is going on … it’s a costume,’ one person can be heard yelling.

Another added: ‘It’s a fake gun.’

Police said the crowd dispersed about an hour later, and that no officers were injured.

Inquiries into the incident are continuing.