I had the same thing happen a couple of days ago. If it is a major overflow you will need some sort of blow off tube. If just a bit and you are without a blow-off tube, a narrow tube that will fit into the hole of the airlock with a good seal might work. You might have something this size with your bottling equipment if you have any.
Things should die down in about a day or so depending on yeast used.
Make Beer, Not War.