This blog details tactics used by "global guerrillas," hence its name. The post that I linked to deals with the terror-tactic of swarming. As I understand it, this emulates the action of a swarm in nature, making it difficult for the target to respond effectively to the overall attack, killing or capturing a few of the many, leaving the attacking force mostly intact.

This is one of the tactics I have feared being used here if the terrorists had enough numbers.