Let's take the argument further. Let us look at what happens if this sort of attack were to be perpetrated at a polling station on the day of the vote. Or even multiple such locations, those responsible somehow having the resources and planning to do so. And do so again the next polling date. And again the next.
Now, I'm pretty sure that this won't happen to me, ever, so consider it false bravado if you will, but even if it did become a possibility then what good would it do to suspend, postpone or otherwise shy away from elections? If there are enough potential perpetrators out there to cause significant disruption to nullify all attempts to get an electoral result then we have problems many magnitudes greater than we have now. Until then, our admittedly flawed and imperfect system should soak up the efforts of the disruptive elements, and if it gets to the point of police and military guards at every ring of steel around each and every primary school being used to vote in, metal/explosive-detecting archways puntuating their perimiter to allow access to the thoroughly swept and scanned grounds (manholes welded shut, attic spaces examined in millimeter-wave, IR, X-ray backscatter, the works), overlooking buildings examined for snipers, all non-essential air-traffic cancelled, anti-drone hawks on standby, anti-hawk drones too... If all that has to happen, then our problem is not that we didn't postpone the prior electoral processes early enough "until we know what the hell is going on".
The conceptual terrain between here and there is too broad a field to plough in one day. Right now the answer is to Keep Calm And Carry On Voting, and I would say the same if another outrage happened today, tomorrow, and right up to the day itself. To seriously contemplate otherwise just does not compute... But it's not for me to say, only to opine.
(re: Pausing campaigning, it needs to be across the board, by agreement, replace all partisan soapboxing with "vote for whoever, but vote" for the statutory 24 hours, and let the voters punish those that try to break that truce, but I'll let the party machines work out their responses and responses to the other responses, then the public work out who had the moral best way of dealing it, if it's enough to swing things. As above, if the perpetrators earn a delay, by their actions, that's bad. A day of contemplative thought is not so bad, and may even be good.)