The shooter who killed at least two people on Monday at a Christian school in Madison, Wis., was identified as Natalie Rupnow, a 15-year-old student who later died from what appeared to be a self-inflicted gunshot wound, the police said. The shooter, who went by “Samantha,” opened fire in a study hall classroom with students from several grades at Abundant Life Christian School, said Shon F. Barnes, the Madison police chief. Officers arrived after a second-grade student placed a 911 call...