I don't see why you should have a moments silence because someone ran in front of a car.
Minutes silences are supposed to be to remember those who gave their lives in a war. Not for those who are shot by police because they act strange. Not for those who jump under a bus.
I can understand why you'd have one after a terrorist attack such as 9/11 or 7/7, but a minutes silence should only be used to remember those who died giving their lives in war.