We don't really know that for sure though. NY made it sound like someone would die in that shooting and no one did except the bartender or something. So it could be the same here, maybe they've pin-pointed who they believe is the killer's next target and they've got them at the lab for protection, but when whatever it is hits the lab, that person is killed. Or it could be a random labrat. Just because they said "someone doesn't get up" doesn't necessarily mean someone on the main team will die. And like I said before, even if they do die, doesn't mean they'll permanently die. They could just be clinically dead for a couple of minutes like Delko was.