While her teenage stepson watched her young kids in her living room earlier this month, Chelsea Nelson took a short break in her adjacent bedroom. Then she heard a loud bang. She came out to inspect and saw her stepson “with terror in his face.” Her kids – 2-year-old Jamari and 5-year-old Aliviah – had climbed their couch, pushed through an open window, and fallen from their third-story apartment. She rushed to the balcony, saw their lifeless bodies below and ran out of her apartment. “It was almost like a nightmare, you know, where those staircases just feel like they’re never ending. And for some reason, I just couldn’t catch my footing,” Nelson said. She found her daughter knocked unconscious and bloodied. Her son was knocked out too, but woke up crying soon after she got to them. “No parent deserves to have to go through that. Nobody wants to see their child like that,” she said. As a heat wave engulfs a large section of the United States, doctors and firefighters are sounding an alarm on an old and stubborn foe: kids falling from windows.