An American nightmare is unfolding Wednesday afternoon at a North Broward high school where a former student came onto campus and opened fire, killing and injuring multiple people. Details remain cloudy amid a flurry of police activity at Marjory Stoneman Douglas High School in Parkland off the Sawgrass Expressway. Students, who heard a fire alarm go off just before dismissal, followed by guns shots, fled off campus and hid under desks as police sped to the scene. Parents, blocked from getting onto campus, stood by helpless. Robert Runcie, superintendent of Broward Schools, is reporting “numerous fatalities” in the terrifying attack,...