Sarnia police say a person was sent to London hospital following an incident early Sunday morning and an officer was later assaulted making an arrest.
They say officers responded to the homeless shelter in central Sarnia at around 4 a.m. Sunday.
Witnesses say a 59-year-old was the victim of a vicious, unprovoked attack and was taken to hospital with serious injuries.
Just before 10 a.m., police say an officer located a suspect on Maria Street.
It's alleged the suspect began fighting and wrestling with the officer who tried to call for backup but there were radio transmission problems.
The pair fell to the ground, and the suspect allegedly continued to punch and strike the officer.
Paramedics arrived and helped the officer and there were no serious injuries in the arrest.
Colin David Parlette, 37, faces charges of aggravated assault, and assaulting a peace officer.
Police said he also had an outstanding warrant for a number of other criminal charges.