There was no reaction really, fill-flash in day light isn't really blinding, I don't think they even noticed/cared.
I guess I shoot on the streets with the mentality that I am a tourist looking for interesting scenes. I wasn't specifically looking for "victims" or make anyone look bad, rather I try to look for meaningful or out of ordinary situations where these people happen to be part of the environment that makes up the whole composition I mean to shoot.
I find that once I start to think of street photography this way, I don't feel that I am doing anything wrong or sneaky, and feel more confident about the activity.