Announced just a few hours ago. For a report with enough distance to be impartial, I suggest Canadian Running magazine.
Whether the decision was made due to (significant) negative public opinion and the political fallout that comes with it, or the realization of how bad things are, who knows. Sometimes it takes days to discover the true extent of a disaster.
This is one of those situations in which there are no good choices. But the way in which the decision was made–saying on Tuesday that the race would go forward, confirming on Wednesday, and then canceling after the lion’s share of runners and press had arrived–appears to have pissed off the greatest number of people possible.