Five injured in stabbings across Sydney

Four young men and another in his late 40s have been caught up in a spate of overnight stabbings across western Sydney.

At Whalan, at 12.45am on Sunday, officers found a 25-year-old man suffering multiple stab wounds to his torso.

They were told he had been involved in a fight with a number of people following a party at a nearby home.

A broken glass bottle was taken for forensic examination, and he is in a critical but stable condition at Westmead Hospital.

Just over an hour later, officers were called to a different home in the same suburb, where a 20-year-old man had a wound to his forearm.

He told them he was stabbed during an altercation nearby. He's also in Westmead Hospital with injuries not considered life-threatening.

Detectives are yet to determine whether the Whalan incidents are linked.

At Doonside, a 15-year-old boy suffered stab wounds to his abdomen and arm, allegedly after an argument with another teenager known to him.

Officers recovered a knife from a nearby drain and an 18-year-old was arrested and charged with intent to cause grievous bodily harm.

Earlier at Northmead, a 19-year-old man was taken to Westmead Hospital with a stab wound to the abdomen.

And a 49 year old man went to Cabramatta police station with multiple stab wounds to his arm saying he'd been the victim of a home invasion. A crime scene has been established at a unit.

Meanwhile in Sydney's east, police cracked down on unauthorised gatherings in bushland areas, with three people charged.

Officers from Eastern Beaches Police Area Command, Central Metropolitan Region Operational Support Group and PolAir were involved in dispersing people from Malabar Head National Park.

A 27-year-old Bellevue man was charged with having cocaine, LSD tabs and cannabis in his possession.

In a separate event at Henry Head within the Kamay Botany Bay National Park, a large number of people fled as police patrolled the area.

Sound and lighting equipment was seized and two men were arrested after failing to move on.

Acting Superintendent Samantha Fordy said unauthorised gatherings of the type would not be tolerated and posed a serious safety risk to attendees and responding police.

"The local community and environment are also being impacted by the noise and the rubbish left behind, she said.

"Police will work closely with officers from Randwick City Council and the National Parks and Wildlife Services to target these events and prosecute offenders accordingly."