That is really sad and discouraging!
Do you know if it was early blight or late blight? I'm not sure, but I believe late blight is more virulent and kills plants quicker.
Either way there is at least a couple weeks, I think, between when symptoms first appear and when you have a dead plant. Did you try to do anything in that time to save them?
It is easier to prevent fungal diseases than cure them, and fungicides work better preventatively.
Now that this has happened, you need to avoid planting tomatoes or potatoes in those beds for a few years, if at all possible. The disease spores will be in the soil.