I was involved in a similar situation. It all happened here: https://goo.gl/maps/bfRW5Kn2Q9Q2 I was working as a Mobile Security Guard patrolling downtown buildings at night. I was checking the two buildings you can see in the street view, the Urban Oasis Tower (called the Macmillan Building at the time) and the Canada Building.
I was coming out of the Canada Building from the back alley walking out to my car when I heard glass break. Then right away I saw 2 guys and a girl run out from Schmata with a bunch of merchandise in their hands. Right away I got on my cell phone to the police and told them I was witnessing a robbery in progress. I watched where the burglars were going and kind of followed them from a distance, they hadn't seen me. They stopped across the street in front of the Royal Bank. I could already hear the police coming, their HQ was only a couple blocks away and I still had the 911 operator on the phone. I don't know what I was thinking but I walked towards them. As I crossed the street the two guys saw me and took off running. The girl froze and walked up and grabbed her. I remember trying to hang onto her with one hand while also talking to the 911 operator. She tried to get away, but quickly realized I really overpowered her, and adrenaline was giving me a death grip on her wrist. I only had to hold onto her for probably only 30 seconds and there were suddenly police cars everywhere! I'd never seen that kind of response from the police, it was pretty impressive.
I handed the girl over and then went with the cops back to the HQ and wrote a police report and that was that. The story made the paper, I think my Mom saved the clipping.