A system, a closure, and method for sealing a percutaneous puncture in a blood vessel. The puncture includes a tract leading to it from the skin of the being. The system includes an introducer sheath, a positioning device, a hemostatic puncture closure, and a deployment instrument. The positioning device positions the introducer sheath at a desired position within the vessel. The deployment instrument includes a tubular carrier having a distal end storing the closure. The carrier is extended via an introducer sheath through the tract and puncture into the blood vessel. The closure comprises a rigid anchor, a spacer member, a compressed collagen plug, and a thin filament connecting them in a pulley-like arrangement. The anchor has a centrally located domed projection. The carrier ejects the anchor through the introducer and puncture and then draws it against the free end of the introducer. The instrument and introducer are then withdrawn together to pull the anchor against the tissue contiguous with the puncture inside the artery and so that the domed portion of the anchor extends through the puncture. Further withdrawal draws the plug and spacer out of the carrier into the puncture tract, whereupon the spacer engages the domed portion of the anchor to prevent the plug from entering the puncture. A tensioning device limits the force applied to the filament. The carrier also includes a tamper which is used to mechanically deform the plug within the tract. Hemostasis occurs rapidly and the plug seals the tract.