Police and paramedics were called to the intersection of William and Howick streets in the early hours of New Year's Day after receiving information that a group of people were fighting.

Chifley Police District station supervisor Sergeant Darryl Goodwin said while no charges had been laid so far in relation to the alleged assault, investigations into the incident remain ongoing.

Officers will be reviewing closed circuit television footage from cameras in the area and will be interviewing witnesses.

Sergeant Goodwin said initial investigations suggest one group of people had been having drinks at a CBD business, which was closed, before going outside onto William Street.

A second group of three to four males, believed to aged between 15 and 17 years, was in the vicinity at the same time.

Following an exchange of words, it is believed one of the young males allegedly hit a 20-year-old man, who fell back and hit his head on the ground.

Paramedics were called and the man was treated at the scene before being transported to Orange Hospital with non-life threatening injuries.

He has undergone treatment scans and remains in Orange Hospital in a stable condition.

Sergeant Goodwin said when police arrived at the scene one of the group of young males allegedly kicked one of the investigating officers.

The teenager was arrested and charged as a result.

Police established a crime scene, taping off the area between Howick and William streets as they continued their investigations into the incident.

Police returned to the area on Friday morning for further investigations before the crime scene tape was removed at around 11am.

Investigations into the incident remain ongoing.

Anyone with information that may help police is asked to contact Crime Stoppers on 1800 333 000.