Dream of kids, bike, diseases

People are getting diseases and turned into zombies. My friend and I are stuck in the same household with a bunch of other kids that are sick, but we're not. This one guy that's in charge is also sick and is beginning to turn into a zombie. My friend and I go to the basement to find guns to kill the ones that are turning to zombies. We find some but when we shoot, it turns out that they are water guns! We go in the basement and find a box of Kleenex that says "OPEN". We open it and there's a gun! We see the guy that's in charge go digging for something in the basement, so we hide. I take aim and shoot, but nothing comes out again. He panics and takes off the seat on the exercising bike. The gun's in there! My other friend takes it away from him and shoots him. It's the real gun. The funny thing is that I have had this dream before. In this dream I was looking for the gun because I remembered the area where it was from the previous dream I had.