What is happening at the beginning of episode 6 of The Walking Dead?

So Im watching the walking dead but I don't understand what is going on that the beginning of the episode where the officer is with the sick patient at the beginning in the hospital room, is he dreaming? What is with all the people shooting? I thought they left him at the tree. I've watched the previous episodes so I know whats going on mainly.|||The person they left at the tree is Jim. The officer, Shane, was trying to get Rick, sick patient, to wake up from his coma. In the first episode, Rick get's shot twice and the second time is what induces the coma. When he wakes up, he's alone in the hospital, and eventually he finds Shane and their camp. In the camp, there is an attack and Jim gets bitten. The creators of the show put the flashback scenes in because it helps explain the story and it usually has something to do with the episode. Hope I helped :)|||That's shane trying to evacuate Rick from the hospital. The people shooting are some sort of army type deal killing all the zombies and infected.



Sick patient=Rick.



It's a flashback