Considering the features of a Little One I could imagine that it could wrack havoc in Boulder in no time. Strategy would be simple:
Attack small groups of people, wound and infect as many as possible, jump/ run away, hide a few minutes, attack the next group; in the meantime the number of
Little Ones litteraly explodes. Since the military dudes would react directly most of the military force would focus on this attack like what all the police and military personell did in L.A., which means: As soon as the men are downed, the city/ rescue camp of Boulder would b defenseless. And don't forget: there are/ were not that many soldiers around ...
So: Yeah, it is a frightening scheme, but considering what happened so far it is not even unlikely ...