As noted earlier, Alma's group has grown from the original converts to over double the original size. While many of the members of the church would have lived with Alma, many still lived in Lehi-Nephi, as discussed above. In this instance, however, they have all gathered for one of the sacred days (probably not the Sabbath as they would not be traveling on the Sabbath). They were therefore all together when the revelation came for them to flee.
Textual: There is no break at this point in the 1830 edition. While modern readers see a clear break between the stories of Alma and the next one of Limhi, Mormon did not separate them. Perhaps he linked them together because of the similarity to time. The army that is sent to destroy Alma's people causes Alma's people to leave, but is also the same that figures in the story of Limhi. This near simultaneity of action may be indicated by placing the stories in the same chapter.