That is there wingspan, so about 2 feet on each side, it really isnt that big. If it had that tail I would most defintetly say it was them. Not may other birds have that distinct fork. Pretty cool to see a group like that! I wish I could have seen it, they are amazing flyers.
Florida is the fall home to the Peregrines Falcon (the worlds fastest bird.. can reach speeds up to 200 mph), but most of the predator birds you see here reffered to as falcons are hawks. The Peregrine until recently was on Florida's endangered species list and still is not commonly seen. You almost cant go for a ride without seeing a red-shouldered hawk though.