The 15-year-old who shot up a Wisconsin Christian school killed a substitute teacher who was covering for another educator who had gone on vacation this week, according to a parent.

Police are investigating why a teenage girl brought a handgun to a small Christian school in Madison, Wisconsin and opened fire, fatally shooting a student and a teacher and wounding several others — casting the tight-knit religious community into mourning just days before the school was set to close for Christmas.

A teacher and teenage student were killed and six others hurt in a shooting at Abundant Life Christian School in Madison, Wisconsin, on Monday, police said.