Yes, exactly. But with a supernatural twist.
I have a more refined idea in my mind, but essentially it was a toxin in the water that killed all these people and more than half of them were children. The rest were no older than 30. They were killed because a rare gene was found in their system that gave them advanced abilities. These people have only begun to show up in one specific area (probably a major city), and their has been an increase birth rate of these people in the current generation. They kill them off so they wont pass the genes on. I was thinking that maybe our characters could be the gifted/cursed humans that somehow evaded the toxin because of their powers. My character has premonitions in her sleep, so I figure that's how she would escape it.
Does that make any sense?