The Special Investigation Unit, a police watchdog, is investigating the circumstances surrounding an incident between Hamilton Police and a man who suffered a serious injury while being arrested early Saturday morning.

Shortly after midnight Saturday, Hamilton Police were called to a disturbance at an A&W restaurant in the area of King Street West and Bay Street North.

Police located the man near Gore Park where there was an interaction as the man was being arrested.

According to the SIU, the man suffered a serious injury and was taken to Hamilton Health Sciences Centre.

A spokesperson for the SIU, Jason Gennaro, told CBC the man was treated at the hospital and released into police custody.

The SIU is an arm's length agency designated to investigate deaths, serious injury, or allegations of sexual assault involving police services.

Three officers are involved in the investigation — one is the subject officer and two are witness officers.

Investigators are continuing to gather and analyze evidence.

The SIU is asking anyone with information about this investigation to contact the lead investigator at 1-800-787-8529.