The 15-year-old suspect in a Michigan school shooting that left four people dead and seven injured was on Wednesday charged with a range of crimes, including terrorism and murder.

Student Ethan Crumbley will be tried as an adult in connection with Tuesday's shooting at Oxford High School, 30 miles (50 kilometers) north of Detroit.

"This was not just an impulsive act," Oakland County Prosecutor Karen McDonald said at a press conference when announcing the charges: 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.

Because he's being charged as an adult, Crumbley faces life in prison.