Looked to me like those walkers in the tents were shot when they were humans, and then they turned into walkers. If you watch the episode again you will notice that those walkers who were wrapped up in the sleeping bags had blood circles on those sleeping bags that could have been made from bullets shot into them. Did those people lock themselves in that small hallway, set up camp to be safe from the apocalypse only to be killed by....perhaps....the crew in the hospital that is holding Beth?

As for the bodies that Daryl dragged out and burned.... those were the bodies of a mother and small child who had died.