Alma 16:3

And now it came to pass before the Nephites could raise a sufficient army to drive them out of the land, they had destroyed the people which were in the city of Ammonihah, and also some around the borders of Noah, and taking others captive into the wilderness.

Before the Nephites could gather enough soldiers to force them out of the land, the Lamanites had destroyed the people in Ammonihah. They also destroyed some people around the borders of Noah. They took others as prisoners into the wilderness.

Before the Nephites could gather an army large enough to push them back, the Lamanites had wiped out everyone in Ammonihah and some people near the borders of Noah. They dragged other captives off into the wilderness.