Detective Acting Sergeant Wayne Ryan, of the Warrnambool police crime investigation unit, said there had been a significant increase in home invasions during the past couple of years.

"It's very worrying considering the age of the offenders and the victims," he said.

"The male victim suffered a fractured nose which will require plastic surgery. The increase in aggravated burglaries is not just limited to Warrnambool but is part of a statewide trend.

"In this case we have four very young men willing to commit this sort of offence where the outcomes can be severe and consequences life long - for both the offenders and the victims," he said. 

Detective Acting Sergeant Ryan said three 17-year-olds male youths and an 18-year-old man went to an Ellerslie Grove address in Warrnambool on Tuesday night.

One of the 17-year-olds was known to the residents of the unit.

A teenager knocked on the door about 11.15pm and a female occupant answered the door.

They pushed past her and entered a lounge room where an 18-year-old man was assaulted.

During the beating, another female tried to intervene in an attempt to stop the assault.

She was grabbed by the head by one of the quartet and her head was slammed onto floor a number of times.

Police were called and one the way to the address came across the four young men.

One ran off while the others were identified, arrested and transported to the Warrnambool police station.

 The young man who fled was arrested at 1.30am on Wednesday.

The quartet were all charged with aggravated burglary and associated offences.

Three were released on bail to appear in court next week.

One of the 17 year old had to appear in court because he was already on bail charged with other offences.

He was bailed again with strict conditions including an overnight curfew.

The male victim suffered lacerations, soreness, marks and bruising to his arms, neck, body and face.

The woman has suffered headaches.

Acting Sergeant Ryan said the victims were left terrified after the home invasion.