Just as Dos Pilas almost immediately launched an attack, so did these Gadiantons. Mormon gives few details, and “destruction” is too tightly associated with Mormon’s editorial conception of the Gadiantons to be very descriptive. Gadiantons, by definition, cause destruction. These are Gadiantons; therefore, they destroy.
However, it is significant that these Gadiantons also cause destruction “among the people of the Lamanites.” Even though Lamanites were in the group that founded the Gadiantons, Mormon sees Gadiantons, Lamanites, and Nephites as separate groups. This will be compatible with Mormon’s later assertion that they represent a foreign element (see Morm. 1:18).