dr. thomas scalea/professor of surgery, university of maryland school of medicine: "i didn't worry about going to be a mass casualty at my school or my city. it's a different world." the campaign began in the aftermath of the sandy hook elementary school shooting... 20 children and 6 adults were killed.dr. scalea says a third of those victims might have been saved with this type of training.and in á2018 more than 30 people have been killed in school shootings across the country."i need to fill it in with the gauze." angel onons lives in the houston area near santa fe high school.angel onons/high school student: "you hear these things on the news and you're like ohhh that's sad but when it's close to you or happening to you it's a different thing altogether."in a mass casualty scenario, every second makes a difference.dr. thomas scalea/professor of surgery, university of maryland school of medicine: "this is a disease of time. the clock starts ticking when you get hurt. not when you get to the hospital."and this is the first line of defense...applyi ng tourniquets...packing wounds...stall