The St. Thomas Police Service (STPS) responded to two assaults Friday with one of them involving a police officer.
Police said Elgin OPP called for assistance of the STPS while conducting breath tests for a 25 year-old man who was in custody for impaired driving.
The man was brought into St. Thomas Police when he allegedly became irate during the breath tests and grabbed the arm of the Officer in Charge, which prompted a physical altercation.
Police said the officer gained control quickly but he remained uncooperative and refused to complete the breath tests.
The man has been charged with assault of a peace officer and was handed a future court date.
Meanwhile, earlier Friday a 17-year-old was arrested after he allegedly instigated a physical altercation with a stranger at the St. Anne's Festival.
Police said he punched the festival goer several times in the head.
Officers also said when they were alerted about the incident they attempted to talk to the teen but they allegedly ran from police.
The youth was located shortly after where they were taken into police custody.
They have since been released on an undertaking to an adult family member.