It's understood there was some kind of altercation with the father and a group of men who were armed with an axe around 3am.

Police say the man's 19-year-old son heard him shouting for help at the rear of his premises, so joined him armed with a tomahawk.

Following a wrestle, the son had his weapon taken from him and was assaulted by the group of men, suffering lacerations to his face and the back of his head and hand, according to officers.

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He then retreated to a friends home and called an ambulance for his dad.

The 42-year-old man was taken to Wollongong Hospital for surgery with multiple facial fractures and lacerations to the head and hand. He is in a serious but stable condition.

A 22-year-old man has been charged with affray and armed with intent. While a 19-year-old man was charged with malicious wounding.

Police investigations continue. Anyone with information should contact Shoalhaven Police or Crime Stoppers on 1800 333 000.

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