OXFORD TOWNSHIP, Mich. (AP) — Authorities say a 15-year-old sophomore opened fire at his Michigan high school on Tuesday, killing three students, including a 16-year-old boy who died in a deputy’s patrol car on the way to a hospital.

Eight other people were wounded, some critically.

Oakland County Sheriff Michael Bouchard says investigators are still trying to determine a motive for the shooting at Oxford High School in Oxford Township.

He says the suspect isn’t talking. The suspect’s father had bought the 9mm Sig Sauer used in the shooting on Friday, Bouchard said, adding that he did not know why the man bought the gun.