A boy who allegedly shot up a Michigan high school on Tuesday, killing four students, was charged as an adult a day later. The 15-year-old was identified by officials as Ethan Crumbley, a student at Oxford High School, where the shootings took place. He was charged with one count of terrorism causing death, four counts of first-degree murder, seven counts of assault with intent to murder, and 12 counts of possession of a firearm in the commission of a felony. Three students died after being struck and a fourth perished Wednesday as a result of his injuries. Oakland County Prosecutor Karen McDonald said her team is confident that they can prove that Ethan planned the attack, citing “a mountain of digital evidence,” including videos and social media posts. She declined to answer whether the shootings appeared to be targeted. “We as prosecutors are ethically bound to not reveal any statements that …