My feeling (hopefully wrong) is that, they are also ending the lives of those who now have fevers, and who are being picked up (presumably to take to hospitals for care... but who would ever know?).
Why would they do that, just isolate the city and drop off food and let it run it’s course? Why would they kill people who get sick, honestly, at this point they are just making things worse I think.
Are you referring to the people that are screaming and fighting off from being carried away? Perhaps that’s what they are afraid of.