I feel having someone go in and talk to the people inside seems to be a good decision. Trapped people tend to be better about talking with friendly people, though they might reflexively shoot at the person who gets inside.
Talking with the people who have the upper hand, outside, might not go as well, especially since they're going after people who essentially look the same as many of our people; might end up mistaking us for 'reinforcements' or something. Still, should probably get their perspective on this as well (though the megaphoning seems to be giving that point).