This paper presents an efficient multi-node broadcasting algorithm in a wormhole-routed 2-D torus, where there are an unknown number of s source nodes located on unknown positions each intending to broadcast a message of size m bytes to the rest of network. The torus is assumed to use the all-port model and the popular dimension-ordered routing. Most existing results are derived based on finding multiple edge-disjoint spanning trees in the network. The main technique used in this paper is an aggregation-then-distribution strategy. First, the broadcast messages are aggregated into some positions of the tones. Then, a number of independent subnetworks are constructed from the torus. These subnetworks, which are responsible for distributing the messages, can well exploit the communication parallelism and the characteristic of wormhole routing. It is shown that such an approach is more appropriate than those using edge-disjoint trees for fixed-connection network such as tori. This is justified by our performance analysis.