I think they were the people who wiped out the race that built the city, long ago.
By doing harm to children, she intended to wipe out the human race.
We might wind up with something that would wipe out not only the visitors, but the human race as well.
In the first chapter, a global conflict wipes out almost the entire human race.
"It seemed more productive than wiping out the human race."
For a while in the twentieth century, they had to live with the very real possibility that war could wipe out the entire human race.
"Why do you want to wipe out the human race?"
They have weapons now that can wipe out the entire race.
I am now prepared to believe that Phase 5 will not wipe out the human race.
"Ben, are we producing the means to wipe out the human race?"