The present invention provides devices, systems, and methods for percutaneously sealing a puncture site in tissue tracts and vessels in human or animal bodies. One system includes a locating assembly that is used to locate the puncture site and can also provide temporary hemostasis when the system is used for closing a vessel puncture. The system also includes a compression assembly comprising a tubular member with a balloon on a distal end thereof. This balloon is at a fixed distance from the locator tip which locates the balloon outside the vessel wall at a predetermined distance. Inflation of this balloon causes forward elongation of the balloon which compresses subcutaneous tissue between the distal tip of the balloon and the vessel wall. This tissue compression against the puncture site is the mechanism that provides hemostasis.