Police say weapons like bats, pipes, sticks and knives were seen in a disturbance at a Kitchener skate park.
Officers were called to the park outside Forest Heights Collegiate Institute shortly after 6 p.m. Wednesday, after being informed of the disturbance.
By the time they arrived, there was no sign of any weapons, although four or five people were hurt. One of them was taken to hospital with a head injury.
The incident remains under investigation. Police believe the people involved in it all knew each other beforehand.