At the very end of Mockingjay, the Capitol citizens are called to the president's residence where they are promised food, shelter, and medicine. Children are encouraged to the very front.
This seems like this is the doing of President Snow — and it has the benefit of creating a human shield for him.
But it also nicely fits into the plans of President Coin — especially the final attack designed to break Katniss. Coin would have had to known that the citizens were coming to the president's residence to plan that final attack.
Did President Coin hack into the Capitol's communication system to broadcast the message attracting the citizens to the president's residence?