Detectives were called yesterday to investigate Saturday night's unprovoked attack that left at least one victim with possible brain injuries and four others recuperating from head cuts and bruising.

They were set upon by up to 20 youths who used bottles and fence palings on their victims before shoving heads through shop windows and kicking them in the face as they were on the ground.

The pregnant partner of one of the victims was forced to watch as the lawless mob continued its attack for several minutes.

Another young woman suffered a leg injury similar to a stab wound, possibly caused by a nail.

The attack was so nasty that at least one of the victims has not been able to leave the house while others did not want to be identified for fear of reprisals.

The attack mirrors similar crimes blamed on members of a group who call themselves "Swansea Boys", or "the 2281s" after their postcode and who have wreaked havoc across the town in the past few years.

It is believed some of the group's members were responsible for an attack on a Belmont house in March after residents confronted rowdy youths outside their Pacific Highway home.

The Newcastle Herald has also reported other residents being attacked by the 2281s after speaking up about the senseless violence in the town.

"This is something which has been going on and on and on and they need to be stopped," a mother of one of Saturday's victims said yesterday.

"These boys were lucky they got out of it with the injuries they did. The people who did this are animals."

Lake Macquarie crime manager Detective Inspector Dave Waddell said police had no reports of attacks since the Belmont incident in March. He said the case had been passed on to his team of detectives to investigate.