A 51-year-old man has been killed and a 23-year-old man is seriously injured after a vicious street brawl in Newcastle overnight.

The two men were fighting in Donald Street, Hamilton South about 3.30am when officers from Newcastle City Police District were called, NSW Police said.

When they arrived, officers were told the men left the area in a vehicle possibly driven by a third man.

A man has been killed after a stabbing in South Hamilton. (Nine)

Not long after, police found the body of the 51-year-old man and the injured 23-year-old at a Coady Street, Hamilton South home.

The injured man was rushed to John Hunter Hospital for emergency surgery.

Police at the scene of a fatal stabbing. (Nine)

Newcastle police commander Superintendent Brett Greentree said police were investigating and that it appeared the deceased suffered stab wounds.