Own immune system, thanks to medicine that didn t exist until now. and today can save your life. next tonight, to a potential danger in your home. we have reported before on batteries catching fire. now a laptop bursting into flames. abc s kayna whitworth with the warning. reporter: tonight, a frightening moment caught on this california home camera. two teenagers sitting near a laptop charging on the couch, when suddenly, it burst into flames. i was just, like, in shock. we didn t really know what was happening. reporter: one boy blowing out the fire and placing it outdoors. but minutes later, another explosion, and then another. even a fire extinguisher doesn t do the trick. it lights for a fourth time.