An occlusion system includes a delivery catheter having an elongate body defining a delivery lumen, and an occlusion device including a bundle of elongate occlusion wires configured for simultaneous delivery through the delivery lumen. At least a portion of each of the occlusion wires includes a shape memory material and has a preformed shape. The occlusion system includes a delivery configuration in which each of the occlusion wires is positioned within the delivery lumen, urged against the preformed shape, and substantially parallel to a longitudinal axis of the delivery lumen, and a post-deployment configuration in which each of the occlusion wires is released from the delivery lumen and conforms to the preformed shape. According to the preformed shape, each of the occlusion wires has a longitudinal segment remaining parallel to the longitudinal axis and a curved end providing an outward radial force with respect to the longitudinal axis.